Frequent Questions for EPA's Office of Transportation and Air Quality

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  • What is the federally mandated warranty for emission controls on my car?

    The Clean Air Act requires manufacturers of light-duty vehicles to provide two federal emission control warranties: (A) "Performance Warranty" and (B) "Design and Defect Warranty." These warranties are provided by the vehicle manufacturer and apply to used vehicles as well. The warranty period begins from the date of sale to the original owner.

    The Performance Warranty covers repairs which are required during the first 2 years or 24,000 miles of vehicle use (whichever first occurs) because the vehicle failed an emission test.  Specified major emission control components are covered for the first 8 years or 80,000 miles (whichever first occurs). The specified major emission control components only include the catalytic converters, the electronic emissions control unit or computer (ECU), and the onboard emissions diagnostic (OBD) device or computer. If you are a resident of an area with an Inspection and Maintenance (I/M) program that meets federal guidelines, you are eligible for this warranty protection provided that:

    • Your car or light-duty truck fails an approved emissions test; and
    • Your vehicle is less than 2 years old and has less than 24,000 miles (up to 8 years/80,000 miles for certain components); and
    • Your state or local government requires that you repair the vehicle; and
    • The test failure does not result from misuse of the vehicle or a failure to follow the manufacturers’ written maintenance instructions; and
    • You present the vehicle to a warranty-authorized manufacturer representative, along with evidence of the emission test failure, during the warranty period.

    The Design and Defect warranty covers repair of emission control or emission related parts which fail to function or function improperly because of a defect in materials or workmanship for 2 years or 24,000 miles (whichever first occurs), and the specified major emissions control components mentioned above for 8 years or 80,000 miles (whichever first occurs). The manufacturer can deny this warranty coverage if evidence shows that the emission component failure was caused by improper use or maintenance and not caused by a defect.

    A list of these components and a description of the warranties (PDF) (10 pp, 697K, EPA-420-F-15-035, October 2015) is available on our web site. However, vehicle technology is constantly changing, therefore there may be emissions control components or emissions related components which do not appear on this list. A more complete list can be found in your owner's manual/warranty booklet. The specified major emissions control components, however, are specified in the Clean Air Act  and are the only components subject to the 8 years/80,000 mile federal emissions warranty.

    When you believe you have identified a defective part, or your vehicle fails an emission test, you should follow the procedures for making a warranty claim as identified by the manufacturer in your owner’s manual or warranty booklet. If you plan to have the manufacturer pay for a repair under either of the emissions warranties, you must take the vehicle to a facility authorized by the vehicle manufacturer for repair to give them the opportunity to diagnose and repair it. Note that if your regular repair facility is not authorized by the vehicle manufacturer, they are not obligated to advise you of parts that are covered under warranty. Before giving your automotive technician the “go ahead” to perform repairs, check your owner’s manual/warranty booklet for possible warranty coverage. Additional state laws may apply, so you might want to contact your state Department of Motor Vehicles to find out.

  • Why is there ethanol in gasoline?

    Congress established standards under the Energy Policy Act of 2005 designed to encourage the blending of renewable fuels into our nation's motor vehicle fuel supply. Congress strengthened the renewable fuels program under the Energy Independence and Security Act (EISA) of 2007 to include specific annual volume standards for total renewable fuel and also for the specific renewable fuel categories of cellulosic biofuel, biomass-based diesel, and advanced biofuel. (EISA aims to move the United States toward greater energy independence and security and increase the production of renewable fuels.) The revised statutory requirements also include new criteria for both renewable fuels and for the feedstocks used to produce them, including reductions in lifecycle greenhouse gas emissions over the fuels they are replacing.  Congress directed EPA to develop and implement regulations to ensure that, over time, transportation fuel sold in the United States makes up a minimum volume of renewable fuel in the transportation fuel pool. Although ethanol blending is not required, just about all refiners are adding 10% ethanol to gasoline (E10) in order to meet the Regulations and Volume Standards under the Renewable Fuel Standard Program. However, there is no prohibition on a refiner continuing to offer a grade of ethanol-free gasoline for use in lawn and garden equipment, boats, etc.

  • Does the fuel used in fuel economy testing contain ethanol?

    EPA's test fuel for light-duty gasoline-fueled vehicles does not currently contain ethanol or other oxygenates. However, EPA does account for the impact of low-level ethanol blends in our fuel economy estimates. Ethanol has a lower energy density than gasoline—about 1/3 less energy per gallon. That means a car operating on E10 (10 percent ethanol and 90 percent gasoline) would require about 3 percent more fuel to travel one mile than a car operating on gasoline and thus have about 3 percent lower fuel economy. EPA adjusts the fuel economy label estimates downward by about 10 percent to account for a variety of factors that are not currently accounted for during laboratory fuel economy testing, such as tire under-inflation, wind, hills, and road conditions. It also includes a 1.5 percent downward adjustment to account for the average national ethanol content.

    Vehicles that are going to be sold in California must be certified to meet California’s emission standards. (The Vehicle Emissions Control Information (VECI) label, found under the hood of all cars and light-trucks, will list if the vehicle complies with the California standards.) Vehicles certified to meet California LEV-III emission standards for 2015 to 2025 model years are required to be tested for tailpipe emissions using E10 test fuel. (For more information, please visit: Amendments to the Low-Emission Vehicle Program - LEV III.)

    In March 2014, EPA finalized Tier 3 emission requirements which will begin with 2017 model year vehicles. The final rule also updated the federal emissions test fuel to contain E10 to better match today’s in-use gasoline and also to be forward-looking with respect to future ethanol and sulfur content. The new test fuel specifications will apply to new vehicle certification, assembly line, and in-use testing. Although Tier 3 vehicles will be tested on E10 test fuel for tailpipe emissions in the near future, EPA has not yet developed procedures to calculate fuel economy of those vehicles which are tested on low levels of ethanol (E10 to E25). For more information, please see: Final Rule for Control of Air Pollution from Motor Vehicles: Tier 3 Motor Vehicle Emission and Fuel Standards. Additional information about fuel economy and EPA's test procedures are available at:

  • How can I find out the amount of carbon dioxide (CO2) my car emits?

    The website has a feature that gives carbon dioxide emissions estimates from your car or light truck. To find this information, use the “find a car” feature on and choose the correct make and model. Once the vehicle you are interested in is displayed, click on the “Energy & the Environment” tab and scroll down to the “Greenhouse Gas Emissions” section (see screen shot below).

    amount of carbon dioxide (CO2) of car emits

    CO2 emissions can be shown to include either tailpipe emissions alone, or to include “upstream” emissions from greenhouse gases emitted from all steps in the production, refining, distribution of the fuel the car uses. Emissions related to vehicle manufacture is excluded.

    If you are looking for an aggregate list of data, the Test Car List Data Files would be the best source; they are available on our web site at: Data on Cars used for Testing Fuel Economy. Click on the comma-delimited file for the appropriate model year and it should open up in a spreadsheet, such as Excel. (If it does not open up as a spreadsheet then save the file to your hard-drive and open it from your spreadsheet software.) The list is in order by manufacturer and model. The CO2 emissions are listed in column with the header name "CO2."

  • What are the health concerns associated with living, working, or attending school near major roads?

    Air pollutants from cars, trucks and other motor vehicles are found in higher concentrations near major roads. People who live, work or attend school near major roads appear to have an increased incidence and severity of health problems associated with air pollution exposures related to roadway traffic including higher rates of asthma onset and aggravation, cardiovascular disease, impaired lung development in children, pre-term and low-birthweight infants, childhood leukemia, and premature death.

    Pollutants directly emitted from cars, trucks and other motor vehicles are found in higher concentrations near major roads. Examples of directly emitted pollutants include particulate matter (PM), carbon monoxide (CO), oxides of nitrogen (NOx), and benzene, though hundreds of chemicals are emitted by motor vehicles. Motor vehicles also emit compounds that lead to the formation of other pollutants in the atmosphere, such as nitrogen dioxide (NO2), which is found in elevated concentrations near major roads, and ozone (O3), which forms further downwind. Beyond vehicles’ tailpipe and evaporative emissions, roadway traffic also emits brake and tire debris and can throw road dust into the air. Individually and in combination, many of the pollutants found near roadways have been associated with adverse health effects.

    People who live, work or attend school near major roads appear to have an increased incidence and severity of health problems that may be related to air pollution from roadway traffic. Health effects that have been associated with proximity to roads include asthma onset and aggravation, cardiovascular disease, reduced lung function, impaired lung development in children, pre-term and low-birthweight infants, childhood leukemia, and premature death. Other than air pollution, road noise may also play a role in the health problems associated with roadway exposure.

    For answers to related questions, please visit the How Mobile Source Pollution Affects Your Health web page.

  • I have invented a device/fuel additive for cars that will increase fuel economy and reduce emissions. Will EPA test it and certify it for me?

    EPA has a voluntary program called the "Aftermarket Retrofit Device Evaluation Program," (also known as the "511 Program") to evaluate the test data submitted by inventors of aftermarket devices for light-duty vehicles. The purpose of the program is to generate, analyze, and share technical data; it does not approve or certify retrofit devices. “Retrofit device” or “device” means any component that is designed to be installed in or on an automobile (as an addition to, as a replacement for, or through alteration or modification of, any original component, equipment, or other device); and that any manufacturer, dealer, or distributor of the device states it will provide higher fuel economy and/or lower emissions than would have resulted with the automobile as originally equipped, as determined by EPA regulations. The term also includes fuel additives for use in an automobile.

    In order for EPA to undertake a formal technical evaluation of such a device, there are a number of steps that an inventor, owner, or investor must follow. Applications must contain complete independent test laboratory test reports which demonstrate a statistically significant improvement in fuel economy and/or emissions reduction. EPA will provide technical assistance in designing the test program to be performed at an independent laboratory. A complete description of the evaluation program, including an application for testing at EPA's National Vehicle and Fuel Emissions Lab, is available at: Evaluation Program for Aftermarket Retrofit Devices. A list of independent testing labs is also available at: Independent Vehicle Emissions Testing Laboratory Listing (PDF)(2 pp, 87.4 K, EPA-420-B-13-054, November 2013). (Please be aware that EPA provides this list as a reference only. EPA does not endorse any laboratory on this list and does not certify that they perform emission testing according to the Code of Federal Regulations (CFR), Title 40, “Protection of the Environment.”) For confirmatory testing at its laboratory, EPA develops the test program in coordination with the applicant, analyzes the test results, and writes an official report summarizing the results in the Federal Register.

    Fuel additives are included in this program; however, oil additives and lubricants are not. If your technology is a fuel additive, each manufacturer or importer of gasoline, diesel fuel, or a fuel additive is required to register its product with EPA prior to its introduction into commerce. It should also be noted that many of the fuel line devices and liquids sold and associated with vapor bleed devices may be considered additives for the purpose of registration. Registration involves providing a chemical description of the product and certain technical, marketing and health-effects information.  This allows EPA to identify the likely combustion and evaporative emissions. In certain cases, health-effects testing is required for a product to maintain its registration or before a new product can be registered. EPA uses this information to identify products whose emissions may pose an unreasonable risk to public health, warranting further investigation and/or regulation. Information on the registration of fuels and fuel additives is available on our web site at: Register a fuel or fuel additive. In addition, this web page -- List of registration forms for fuels and fuel additives -- contains reporting forms and associated instructions for the registration of fuels and fuel additives (FFARs) (40 CFR 79 Subparts A, B, C, D, and F).  These forms are required to be completed and submitted by producers and importers of gasoline, diesel fuel (including biodiesel) and fuel additives prior to their manufacture or import.

    EPA issues a complete report for any product evaluated by EPA under the 511 Program. Please be aware that even if EPA has verified the fuel-saving and/or emission reducing benefits of a particular technology or device, EPA does not certify, approve, or endorse any product tested in this program nor any independent laboratory nor the results of any independent laboratory testing.

  • How much air pollution does a car produce when it’s moving and when it’s idling?
    The amount of pollution that a vehicle emits depends on many factors, such as the vehicle’s age and accumulated mileage, the type of fuel used, and the weather conditions. EPA has developed computer models that estimate the average emissions for different types of highway vehicles. In order to give a general estimate, we have a fact sheet that gives the average annual emissions and fuel consumption for passenger cars and light trucks:
    We have another fact sheet that explains the amount of pollution that is created when vehicles idle that is available on our site at: 

    When a car idles for more than 30 seconds, it has several negative effects, such as increasing air pollution unnecessarily, wasting fuel and money, and causing excessive wear or even damaging a car’s engine components, including cylinders, spark plugs, and the exhaust system. Contrary to popular belief, idling isn't an effective way to warm up most car engines. Today's automobile manufacturers recommend driving off right away and urge that drivers wait no more than 30 seconds to begin driving, even on the coldest days. Some people worry that restarting the engine might harm the car, but frequent restarting does little damage. Modern engines require much less fuel at startup than most people think. Idling for only 30 seconds uses up more fuel than restarting the engine.

  • What can I do about a car, heavy-duty truck, or train idling near my house?

    EPA does not regulate idling for passenger cars, pick-up trucks, and heavy-duty trucks, but over two dozen states and many cities and local counties have laws that limit the amount of time that a vehicle can idle. For a list of State and local anti-idling laws, please visit the American Transportation Research Institute's (ATRI's) website at: (Please note that we are providing these links for your reference only. In doing so, EPA does not endorse any non-government websites (or the information they contain), companies, or applications. In addition, EPA cannot attest to the accuracy of non-EPA information provided on these third-party websites.) If there is a law for the area you live in, you could follow up with the proper authorities.

    It is common for truck drivers to run their engines to stay warm or cool in their trucks while resting after long hauls. But long-duration idling is costly—to the driver, the fleet owner, and the environment. Some surveys say that trucks idle anywhere from 6-8 hours a day for as many as 250 to 300 days each year. And at current fuel prices, this can cost $6000 or more per year in fuel costs per truck. Each year, long-duration idling of truck engines consume over 500 million gallons of diesel fuel and emits 5.5 million tons of carbon dioxide,100,000 tons of oxides of nitrogen, and 2500 tons of particulate matter into the air. Also, idling can increase engine maintenance costs, shorten engine life, adversely affect driver well-being, and create elevated noise levels. In addition to checking on state or local anti-idling laws, you might also consider contacting the company that owns the vehicle to find out if they have an internal policy against idling.

    EPA’s SmartWay Program has researched, developed, and encouraged the use of a wide variety of strategies to reduce long-duration idling. To learn more about that program, please visit the SmartWay website at: Learn About Idling Reduction Technologies (IRTs) for Trucks. Furthermore, our Clean Schoolbus USA program launched its National Idle-Reduction Campaign to eliminate unnecessary public school bus idling. You can learn more about this initiative on our website at: Clean School Bus: Idle Reduction.

    For locomotives however, EPA has regulations that require technology that reduces the amount of time a locomotive spends idling and applying tighter emission standards to new locomotives generally. EPA is requiring that all newly manufactured and nearly all remanufactured locomotives be equipped with idle reduction technology that will automatically shut locomotives down if they are left idling unnecessarily. In addition, rail carriers can join the SmartWay Program and save money, reduce fuel consumption, and get recognition for their social responsibility and leadership. Reducing idling is one way these companies can improve overall efficiency and reduce fuel costs. They can accomplish this through a variety of technologies and strategies, including automatic engine stop-start systems, auxiliary power units or diesel-driven heating systems, electrical shorepower connections, and company idle-shutdown policies.

    EPA has a series of fact sheets that estimate the amount of pollution that is created when different vehicles idle that are available on our website at:
  • Why doesn’t my car get the same gas mileage that is listed on the Fuel Economy Label?

    The purpose of the fuel economy ratings is to provide consumers with estimates to use in comparing the gas mileage of different vehicles. It is not meant as a guarantee of the gas mileage each driver will achieve. Since no test can simulate all the possible conditions that affect fuel economy, such as climate, driver behavior, road condition, and car care habits, your actual mileage will always vary some from the estimates.

    Fuel economy is measured under controlled conditions in a laboratory using a standardized test procedure specified by federal law. The fuel economy tests (which EPA updated in 2006 to more accurately account for actual driving conditions that can lower fuel economy, such as high speed, aggressive driving, use of air conditioning, and cold temperature operation), are based on a detailed driving cycle (each car is driven in exactly the same way, for exactly the same distance, with the same second-by-second vehicle speeds, to the maximum extent possible). The tests also are conducted under controlled conditions, using gasoline or diesel fuel that meet very detailed specifications. The goal of the laboratory testing is to control as many of the factors that affect fuel economy as possible, to the maximum degree that it is feasible to do so. Manufacturers test their own vehicles following EPA's test procedures—usually pre-production prototypes—and report the results to EPA. EPA reviews the results and confirms about 10-15 percent of them through our own tests at the National Vehicle and Fuel Emissions Laboratory (/vehicle-and-fuel-emissions-testing).

    Additional information about fuel economy testing is available on the following websites:

    It is essential that EPA's fuel economy estimates continue to be derived from controlled, repeatable laboratory tests to enable a standardized or "level playing field," comparison between all vehicle models. Although EPA's fuel economy tests are designed to reflect typical driving conditions and driver behavior, several factors can significantly affect how many miles per gallon (mpg) your car gets: how and where you drive; vehicle condition and maintenance; fuel variations; vehicle variations; and engine break-in (the fuel economy of new cars and trucks improves with mileage up to approximately 20,000 miles; it especially improves in the first 1000-2000 miles). These factors are described in my detail on the following websites: Because some vehicles are more sensitive to these factors than others, the impact of the changes will vary from vehicle to vehicle. For example, the nature of current hybrid technology -- the addition of a battery as a second source of on-board power, sophisticated control systems, and sometimes a smaller engine -- makes a hybrid's fuel economy more sensitive to certain factors, such as colder weather and air conditioning use.  

    Although EPA sets emission standards for pollutants that vehicle manufacturers have to meet, we do not set fuel economy standards for the vehicles currently on the market. Therefore, even if a vehicle does not achieve the EPA fuel economy rating, the manufacturers are not required to re-test or change the car for that specific model year. However, if a significant number of specific vehicle complaints are received, EPA has the option of performing confirmatory tests for the vehicle the following model year.

    Given the above information, what is the best way to get realistic "city" and "highway" fuel economy numbers for your vehicle?  There is no "official" answer to that question, but we can offer you these suggestions.

    • Start with a full tank of gas.  By "full," we mean filling up using a pump that allows you to lock a lever in place and take your hand off the hose and nozzle.  Use the lowest rate of fuel delivery offered (most nozzles have two dispensing rate settings, and some have three). Do not top off -- when the nozzle first shuts off, do not dispense any more fuel.
    • Record your odometer mileage (or, if you have a trip odometer, reset it to zero).
    • Drive at least half the tank, preferably 3/4 to 7/8 of the tank, before refueling.
    • During the time when you are measuring the fuel economy of your vehicle, try to avoid extended idling operation and the use of a remote starter.
    • For "city" driving, a minimal amount of freeway/expressway driving can be included; for "highway" driving, measure when you will be taking longer trips that are predominantly freeway, with relatively little stop-and-go and infrequent engine off/engine restarts.
    • Refuel at the same station, using the same pump and nozzle if possible. At the least, refill with the same brand and grade of gasoline.
    • When refilling, do it as you did in step one -- automatic flow, lowest rate, no top-off.

    To calculate the fuel economy in miles per gallon, take the number of miles driven and divide it by the total gallons purchased at refueling. For an even better estimate, take the average of two or three tanks in each case (city, highway). While there are minor variations over time, this allows you to monitor the vehicle's performance. A sudden drop in fuel economy not explained by the reasons noted below tells you that you may need to have maintenance done on your car.

    If you are interested in seeing what fuel economy other owners of your vehicle are getting, please visit the following website:

    To find out what you can do to improve the fuel economy of your car, please visit the following website: Driving efficiently and keeping your car in shape will make a difference.

    If your fuel economy is excessively low, your vehicle may need to be serviced or repaired. You may want to contact your dealer and ask them to check your vehicle and to determine that there are no outstanding defect reports or service bulletins which may affect fuel economy. The following are some of the diagnostic checks a mechanic will typically conduct for poor mpg:

    • Perform "On-Board Diagnostic System Check" for diagnostic trouble codes (sensors or actuators which may be malfunctioning)
    • Check for dragging brakes
    • Check transmission shift patterns for slipping, use of all gears, lock-up operation
    • Check ignition timing
    • Check owner's driving habits including A/C usage, hard accelerations, carrying heavy loads
    • Check emission control system
    • Check vacuum hoses for leaks, kinks, proper routing
    • Check tire pressure
    • Check fuel type, quality, and alcohol content
    • Check fuel pressure and fuel system for leaks
    • Check air cleaner element
    • Check coolant level
    • Check ignition system for wet plugs, cracks, wear, improper gap, burned electrodes, or heavy deposits, cracking or improperly connected ignition wires
    • Check for proper calibration of speedometer
    • In extreme cases, there may be engine problems such as poor compression or faulty fuel injectors

    If you are not satisfied with the outcome from the dealership, you can take your case to the Service Representative; the contact information should be listed in the owner’s manual. Be sure to document your observations thoroughly.

  • I purchased an ATV in 2012. How will EPA’s 2013 action affect me?

    On April 3, 2013, EPA withdrew its approval of the import and sale of over 70,000 gas-powered on- and off-road motorcycles and all-terrain vehicles because the agency believes that it received either incomplete or falsified certification information. The companies are responsible for violations of the Clean Air Act. While your ATV may be a model that was covered by these voided certificates, you are not responsible for these companies’ wrongdoing and can continue to use your vehicle.

    For more information, please visit: Actions to Void Certificates for Vehicle and Engines

  • How will the Tier 3 vehicle and fuel standards create health benefits for Americans?

    Starting in 2017, Tier 3 sets new vehicle emissions standards and lowers the sulfur content of gasoline, considering the vehicle and its fuel as an integrated system.  Tier 3 is among the most highly cost-effective air quality control measures available. The program is projected to cost less than a penny per gallon of gasoline, and about $72 per vehicle. The annual cost of the overall program in 2030 is projected to be approximately $1.5 billion; however, we estimate that in 2030, the annual monetized health benefits of the Tier 3 standards will be between $6.7 and $19 billion.

    By 2030, the Tier 3 standards will annually prevent:

    • Between 770 and 2,000 premature deaths
    • 2,200 hospital admissions and asthma-related emergency room visits
    • 19,000 asthma exacerbations
    • 30,000 upper and lower respiratory symptoms in children
    • 1.4 million lost school days, work days and minor-restricted activities

    Over 149 million Americans are currently experiencing unhealthy levels of air pollution which are linked with adverse health impacts such as hospital admissions, emergency room visits, and premature mortality. Motor vehicles are a particularly important source of exposure to air pollution, especially in urban areas. 

    The vehicle emission standards combined with the reduction of gasoline sulfur content will significantly reduce motor vehicle emissions, including nitrogen oxides (NOX), volatile organic compounds (VOCs), direct particulate matter (PM2.5), carbon monoxide (CO) and air toxics. Tier 3 will also reduce exposure to vehicle pollution for the millions of people living, working, and going to school near major roads.

    For more information, please visit: Final Rule for Control of Air Pollution from Motor Vehicles: Tier 3 Motor Vehicle Emission and Fuel Standards

  • Over the past several years, what have been the technological and environmental trends in automotive fuel economy?

    EPA’s annual “Light-Duty Automotive Technology, Carbon Dioxide Emissions, and Fuel Economy Trends: 1975 through 2012” report that tracks the fuel economy of vehicles sold in the United States is signaling a significant 1.4 mile per gallon (mpg) increase for 2012 cars and trucks – along with a continued decrease in carbon pollution.

    The expected 1.4 mpg improvement in 2012 is based on sales estimates provided to EPA by automakers. EPA’s projections show a reduction in carbon dioxide (CO2) emissions to 374 grams per mile and an increase in average fuel economy to 23.8 mpg. If achieved, these would be among the largest annual improvements since EPA began reporting on fuel economy. These improvements would more than make up for a slight 0.2 mpg decrease in 2011 that resulted primarily from earthquake and tsunami-related disruptions to vehicle manufacturing in Japan. From 2007 to 2012, EPA estimates that CO2 emissions have decreased by 13 percent and fuel economy values have increased by 16 percent.

    Fuel economy is expected to continue improving significantly under the Obama administration’s historic National Clean Car Program standards.  The program cuts greenhouse gas emissions and would double fuel economy standards by 2025.  The standards will save American families $1.7 trillion dollars in fuel costs, and by 2025 will result in an average fuel savings of more than $8,000 per vehicle. The program will also save 12 billion barrels of oil, and by 2025 will reduce oil consumption by more than 2 million barrels a day – as much as half of the oil imported from OPEC every day.

    The report attributes the improvements to the rapid adoption of more efficient technologies, the increasing number of high fuel economy choices for consumers, and the fact that many automakers are already selling vehicles that can meet more stringent future fuel economy and greenhouse gas emissions standards.

    Compared to five years ago, consumers have twice as many hybrid and diesel vehicle choices, a growing set of plug-in electric vehicle options, and a six-fold increase in the number of car models with combined city/highway fuel economy of 30 mpg or higher.

    The new report can be found at: Light-Duty Automotive Technology, Carbon Dioxide Emissions, and Fuel Economy Trends Report Overview.

  • How will the proposed voluntary Quality Assurance Program for verifying Renewable Identification Numbers be effective in assuring their validity?

    The proposal would provide a recognized means for independent third parties to audit the production of renewable fuel and the generation of Renewable identification Numbers (RINs). Minimum requirements for the Quality Assurance Program (QAP), including such things as verification of type of feed­stocks, verification that volumes produced are consistent with amount of feedstocks processed, and verification that RINs generated are appropriately categorized and match the volumes produced will be enacted. There will also be qualifications for independent third-party auditors and requirements for audits of renewable fuel production facilities, including minimum frequency, site visits, review of records, and reporting. The impacts of this proposal intend to improve RIN market liquidity and efficiency and improve the ability of smaller renewable fuel producers to sell their RINs. As the program is voluntary, there would be no required costs. For more information, please see: Renewable Fuel Standard Program.

  • Why did EPA determine that a request to waive the renewable fuel standard should be denied?

    EPA recognizes that this year’s drought has created significant hardships in many sectors of the economy, particularly for livestock producers. However, the agency’s extensive analysis makes clear that Congressional requirements for a waiver have not been met and that waiving the Renewable Fuels Standard (RFS) would have little, if any, impact on ethanol demand over the time period analyzed.

    EPA has not found evidence to support a finding of severe “economic harm” that would warrant granting a waiver of the RFS. The decision is based on economic analyses and modeling done in conjunction with the U.S. Department of Agriculture (USDA) and U.S. Department of Energy (DOE).

    For more information about EPA's decision, please go to: Announcements under RFS.

  • What were the recent fuel waivers EPA granted, where do they apply, and how do they help alleviate disruptions in the fuel supply?

    EPA has authority to temporarily waive certain fuel requirements in emergency situations when the fuel supply suffers major disruption. In such circumstances EPA works closely with state and other federal agencies to determine an appropriate response.

    As a result of the potential disruption in the supply of fuel following Hurricane Sandy, EPA has exercised its authority under the Clean Air Act to temporarily waive certain federal clean gasoline requirements for gasoline sold and distributed in Tennessee, North Carolina, South Carolina, Mississippi, Georgia, Alabama, District of Columbia, New York, Maryland, Connecticut, Delaware, Massachusetts, New Jersey, Pennsylvania, Virginia, New Hampshire, and Rhode Island. The waivers were granted by EPA in coordination with the Department of Energy.

    Former EPA Administrator Lisa P. Jackson determined that extreme and unusual supply circumstances exist, which may result in a temporary shortage of gasoline compliant with federal regulations, and allows for the use of home heating oil as a fuel use in most emergency generators, in a select area The federal waivers will help ensure an adequate supply of fuels in the impacted states.

    The first waiver applies to the blending of reformulated gasoline into conventional gasoline in the Northeast. Hurricane Sandy impacted the ability to off-load reformulated gasoline into New York and New Jersey terminals, potentially impacting the pipeline’s ability to deliver fuel to additional terminals across the Northeast. The waiver will provide the pipelines with the ability to off-load either reformulated or conventional gasoline into terminals, allowing the pipeline to continue to supply fuel to areas impacted by the hurricane.

    The second waiver is for the state of New Jersey and applies to the use of home heating oil in most emergency generators and pumps. The waiver temporarily allows the use of heating oil in emergency generators and pumps if ultra low-sulfur fuel is not available. The waiver will not apply to a small subset of diesel engines used in generators and pumps that could be damaged by the high sulfur fuel.

    For more information, please see the Office of Enforcement and Compliance Assurance's fuel waivers page.

  • Do those products that claim to improve fuel economy or lower emissions really work? Some say that they are EPA-certified.

    There are many fuel additives and/or aftermarket devices on the market that claim to save fuel and/or lower emissions. Some even claim they are approved or certified by EPA.

    Under the Clean Air Act, a fuel additive (any substance or compound intended to be added to gasoline or diesel fuel) must be registered with EPA.  This means that the manufacturer of the product must provide EPA with certain information concerning the chemical composition of the additive, as well as submitting data to EPA that provides reasonable assurance that the use of the additive will not increase emissions of regulated air pollutants and will not pose a health or safety threat to the public. The registration requirements do not address the efficiency of the product or require any demonstration that the claims made for the product are valid (typically, "better fuel economy," and sometimes also "reduced emissions" or "engine life benefits").

    Those marketing such products take advantage of this distinction, citing the fact that the product is "registered with the US EPA" and sometimes citing the applicable section of the Code of Federal Regulations (i.e., "under the provisions of 40 CFR Part 79") to foster the impression that EPA has somehow "approved of" or endorsed the product. For more information on the process by which fuel additives must be registered with EPA, and exactly what this does and does not imply, please see: Register a fuel or fuel additive.

    We have a program under which formal evaluation test programs are performed on aftermarket devices (generally, mechanical objects that are attached to or installed on a vehicle by the consumer) and on certain fuel additives. However, EPA does not certify, approve, or endorse any product tested in this program nor the results of any independent laboratory testing. EPA issues a technical report for those products and additives that we have tested and evaluated; these reports are available on our site at: Registered fuels & fuel additives under 40 CFR Part 79.

    None of these products were found to produce statistically significant benefits in terms of fuel economy or exhaust emissions. When we explain all this to someone, the usual question we get back is "Why doesn't EPA stop them from doing this?"  EPA does not have the authority (or the resources) to attempt to stop such products from being marketed.  When the Federal Trade Commission (FTC), which can go after companies for false advertising, does manage to stop a company from marketing anything along these lines, the company and/or the product simply resurface under new names. 

    Many people want to believe that there are in fact such "magic products" that will somehow greatly improve your vehicle's fuel economy (and hence reduce the costs of fuel), but when it comes to products and claims such as this, it’s wise for drivers to be skeptical. For more information, please read the following fact sheets on gas-saving products:
  • How can I get a copy of the Certificate of Conformity for my car?
    Vehicle Emission Information

    To request or find a Certificate of Conformity and/or Certificate Summary Information sheet, you need to know the Test Group number (for light-duty cars and trucks – model year 2001 or later) or the Engine Family number (for pre-2001 light-duty cars and trucks). This information is listed on the “Vehicle Emission Information” label/sticker located under the vehicle’s hood. The number has 11 characters using both numbers and letters.

    For Vehicles 2003 or Later

    If your vehicle’s model year is 2003 or later, you can get the Certificate of Conformity and the Certificate Summary Information sheet by:

    • Going to the advanced search page for the Document Index System
    • Choosing “Certificates of Conformity” for Compliance Document Type
    • Choosing the industry (e.g., “Light-Duty Vehicles and Trucks” for passenger cars, trucks, vans, and SUVs)
    • Choosing the appropriate model year of the vehicle
    • Choosing the appropriate manufacturer of the vehicle
    • Typing in the vehicle model
    • Skip the “Keyword Search,” “Engine Displacement, Number of Cylinders, “Emission Control System,” and “Document Date on and after” fields
    • Typing in the Test Group or Engine Family number
    • Clicking on the “Search” button
    • Saving and/or printing the PDF file.

    For Vehicles 2003 or Before

    If you need a Certificate of Conformity or Certificate Summary Information for a vehicle with a model year before 2003, send the following information to EPA’s Imports Hotline ( For telephone assistance, please call the Imports Team at (734)-214-4100. Or send fax requests to (734) 214-4676.

    • Model year of vehicle
    • Manufacturer of vehicle
    • Model of vehicle
    • Test Group number (only applies to light-duty cars and trucks – model year 2001 or later)
    • Engine Family number (only for pre-2001 light-duty cars and trucks, and nonroad and heavy-duty engines/vehicles)
    • Your name
    • Contact information (address, email address, or fax number where you want EPA to send the Certificate of Conformity to)

    For Importing

    All of the requirements for importing a vehicle into (or exporting from) the United States are described on the Imports site.

    If you have any questions, please call the EPA Imports Hotline at 734-214-4100 or email them at

  • How can I get a copy of the Certificate of Conformity for a nonroad or a heavy-duty highway engine?

    To obtain the Certificate of Conformity data for a heavy-duty highway or nonroad engine, please send the following information to EPA’s Imports Hotline ( For telephone assistance, please call the Imports Team at (734) 214-4100. Or send fax requests to (734) 214-4676.

    • Model year of engine
    • Type of engine (e.g., nonroad gasoline or diesel, heavy-duty highway gasoline or diesel)
    • Manufacturer
    • Engine Family # (11 characters using both numbers and letters – printed on the emission label, which is located on the engine or in the engine compartment of the equipment)
    • Your name
    • Contact information (address, email address, or fax number where you want EPA to send the Certificate of Conformity to)

    For Importing/Exporting

    If you are exporting a heavy-duty highway engine/vehicle or nonroad engine/equipment to another country, the government sometimes requests the test data. You will need to know the Engine Family number (found on the emission label) to obtain this information. You can access test data for heavy-duty highway engines or nonroad engines for 1998 to the present on EPA’s websites as follows:

    • Go to: Engine Certification Data
    • Choose the type of engine
    • Choose the model year
    • Depending upon the model the information will be in either Excel spreadsheet and/or File Maker (in File Maker search by the manufacturer or engine family name).
    View requirements for importing a vehicle into (or exporting from) the United States:

    If you have any questions, please call the EPA Imports Hotline at (734) 214-4100 or email them at

  • I just bought a used car and discovered the catalytic converter is missing. Is that legal?

    The act of removing a catalytic converter without replacing it with an approved replacement (known as "tampering") is illegal under federal law and is of great concern to EPA because of the high pollution levels that are emitted by vehicles without properly functioning emission controls. The original antitampering law was part of the Clean Air Act of 1970; it applied only to manufacturers and car dealers. The antitampering law was expanded by the 1977 Clean Air Act Amendments to apply to all automobile repair facilities, commercial mechanics, and fleet operators. And the 1990 Clean Air Act Amendments (CAAA) broadened the tampering provision even further; it now applies to everyone, including car owners. Here is the text from the 1990 CAAA:

    "Section 288 – Enforcement: (b) TAMPERING WITH VEHICLE EMISSION CONTROLS –

    (1) Section 203(a)(3) (42 U.S.C. 7522(a)(3)) is amended to read as follows:

    '(3)(A) for any person to remove or render inoperative any device or element of design installed on or in a motor vehicle or motor vehicle engine in compliance with regulations under this title prior to its sale and delivery to the ultimate purchaser, or for any person knowingly to remove or render inoperative any such device or element of design after such sale and delivery to the ultimate purchaser; or

    '(B) for any person to manufacture or sell, or offer to sell, or install, any part or component intended for use with, or as part of, any motor vehicle or motor vehicle engine, where a principal effect of the part or component is to bypass, defeat, or render inoperative any device or element of design installed on or in a motor vehicle or motor vehicle engine in compliance with regulations under this title, and where the person knows or should know that such part or component is being offered for sale or installed for such use or put to such use; or '

    (2) At the end of section 203(a) (42 U.S.C. 7522(a)) insert the following:

    'No action with respect to any device or element of design referred to in paragraph (3) shall be treated as a prohibited act under that paragraph if (i) the action is for the purpose of repair or replacement of the device or element, or is a necessary and temporary procedure to repair or replace any other item and the device or element is replaced upon completion of the procedure, and (ii) such action thereafter results in the proper functioning of the device or element referred to in paragraph (3). No action with respect to any device or element of design referred to in paragraph (3) shall be treated as a prohibited act under that paragraph if the action is for the purpose of a conversion of a motor vehicle for use of a clean alternative fuel (as defined in this title) and if such vehicle complies with the applicable standard under section 202 when operating on such fuel, and if in the case of a clean alternative fuel vehicle (as defined by rule by the Administrator), the device or element is replaced upon completion of the conversion procedure and such action results in proper functioning of the device or element when the motor vehicle operates on conventional fuel.'."

    The resale of a vehicle which has already had the catalytic converter removed is not specifically addressed by federal law. Therefore, the person who removed the converter violated federal law, but not necessarily the person who sold the vehicle. However, the sale of vehicles that have had the emission control system removed, disabled, or tampered with may be further governed by state or local laws.

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