Doesn't the EPA test the fuel economy of all new vehicles? Actually, no.

Last week, Hyundai and Kia announced that they had each made errors in the way they tested the fuel economy of their new vehicles. "Honest mistakes" and "human error" were made during their in-house process for determining fuel economy figures that overestimated the rate at which vehicles like the Veloster and Elantra burn fuel. While most models were off by one or two MPGs, highway numbers for the Kia Soul were revised down by six MPGs in one instance.

At this point, you might be saying, wait, automakers get to test their own vehicles? Doesn't the Environmental Protection Agency (EPA) do that?

Actually, no.

Most new cars and trucks in the US never see the inside of the EPA's National Vehicles and Fuel Emissions Laboratory in Ann Arbor, MI. Instead, they are tested by the manufacturers themselves, which often use pre-production prototypes in "a standardized test procedure specified by federal law," and then report those numbers to the EPA. Only 10-to-15 percent of all new models, or about 150 to 200 vehicles per year, are re-tested by the EPA to verify the automakers' numbers. Keep reading below for the full story.
Over the decades, this system has worked well and there's no hint that there are widespread issues of faulty test data being reported back to the EPA and used as official MPG numbers seen everywhere from TV ads to window stickers. Sharon Basel, from GM's Environment, Energy & Safety Communications department, told AutoblogGreen that the "EPA requirements do include a complex series of test and procedures. GM works closely with the staff at EPA to make sure that we have a common understanding and interpretation of those requirements." There is, though, "an ongoing investigation," the EPA says, without giving more details, so we might learn that errors are more widespread than anyone now suspects.

There are a number of ways to manipulate the results.

Here is how the government and automakers are supposed to test fuel economy for all non-plug-in vehicles (plug-ins – as well as hydrogen-powered and other alternative powertrains – are a more complicated, separate-but-related issue). The vehicle is placed on a dynamometer in a lab and then put through a series of tests to simulate "typical" trips that represent five different drives: city, highway, high speed, air conditioner and cold temperature. The speeds that the wheels must be spinning are specified, as are the distances and number of stops, and the carbon emissions are measured to see just how clean or dirty the vehicle is. There's a chart detailing these procedures below, and you can get a more detailed description of the EPA's tests here.

Even though the test was updated for 2008 model year and later vehicles, it is still not perfect. If you want to know more, there are two detailed PDFs about the test procedures (1, 2). Jay Friedland, the legislative director at Plug In America, told AutoblogGreen that, "The trickiest issues around EPA testing are the fact that they are indeed self-reported homologation and that there are a number of ways to manipulate the results." Friedland said that the tests are inaccurate enough that the EPA needs to have a "fudge" factor, "which further reduces the combined mileage by a factor of .7 to make the data better match the real world."

Driving Schedule Attributes Test Schedule
City Highway High Speed AC Cold
Temp
Trip Type Low speeds in stop-and-go urban traffic Free-flow traffic at highway speeds Higher speeds; harder acceleration & braking AC use under hot ambient conditions City test w/ colder outside temperature
Top Speed 56 mph 60 mph 80 mph 54.8 mph 56 mph
Average Speed 21.2 mph 48.3 mph 48.4 mph 21.2 mph 21.2 mph
Max. Acceleration 3.3 mph/sec 3.2 mph/sec 8.46 mph/sec 5.1 mph/sec 3.3 mph/sec
Simulated Distance 11 mi. 10.3 mi. 8 mi. 3.6 mi. 11 mi.
Time 31.2 min. 12.75 min. 9.9 min. 9.9 min. 31.2 min.
Stops 23 None 4 5 23
Idling time 18% of time None 7% of time 19% of time 18% of time
Engine Startup* Cold Warm Warm Warm Cold
Lab temperature 68–86ºF 95ºF 20ºF
Vehicle air conditioning Off Off Off On Off

* A vehicle's engine doesn't reach maximum fuel efficiency until it is warm.



I'm reporting this comment as:

Reported comments and users are reviewed by Autoblog staff 24 hours a day, seven days a week to determine whether they violate Community Guideline. Accounts are penalized for Community Guidelines violations and serious or repeated violations can lead to account termination.


    • 1 Second Ago
  • 84 Comments
      Rob
      • 2 Years Ago
      So let me get this straight...the EPA only tests 10-15% of new vehicles equaling about 150-200 vehicles per year? Have they not tested a Kia or Hyundai in the last 3 years? What M-Fing cars are they testing? Seriously!?!?!?! How many 'new' cars are released each year? I doubt 150 all new models were released in 2012. There are what, 30 or so brands, meaning the EPA could test 5 from each, every year. But they dont even need to do that! How many companies release 5 new cars in 1 year? I can see the morons at the EPA now. "This year we will test 72 different variations of the Ford F-150, 21 Dodge Rams, 55 Chevrolet Silvarados and 7 Honda Civics. That will let us know if anyone has fudged an numbers." Government bureaucracy at its finest!
        Hello, Brian
        • 2 Years Ago
        @Rob
        They don't just test new models...and yes, they do have to test every engine/transmission/drive wheel variation of a model. That adds up to a lot more than 150 cars per year. How else will they know that the AWD version really only has a 2 mpg difference? I take it that you don't think it is necessary to test every configuration of a model, but sometimes the differences can be drastic (Chrysler 300 AWD with a 5 spd Hemi vs. RWD 8spd V-6, for example)
          Rob
          • 2 Years Ago
          @Hello, Brian
          You saying the EPA tests every model contradicts what this article states. The manufacturer tests each model, not the EPA, and reports these figures to the EPA. Which brings me to my point above, if the EPA tests 150-200 cars each year, why did they not catch Kia and Hyundai overstating the MPG at some point in the last couple years? I think it is obvious the EPA does a poor job, which is the norm for a government bureaucracy. Testing independently of the manufacturer does not mean you need to test each powertrain combination of a vehicle. If, in your example, the EPA tests a Chyrsler 300 AWD V8 and the MPG is in line with the stated MPG from the manufacturer, there is little reason to believe the results on other 300s will vary. If that same test reveals the AWD V8 300 if off by 3-4 MPG then would be the time to begin to assemble the model line up and test them all. That would make sense to me but I'm not a bureaucrat so what to I know. Thumbs down if you love big government! Thumbs down if you're unable to think for yourself!
      Avinash Machado
      • 2 Years Ago
      So the term EPA cycle is quite misleading?
      jebibudala
      • 2 Years Ago
      Here's my observation... Generally people who buy the "sporty type" cars, such as the ones in question generally drive them well beyond the EPA test cycle procedures, thus will NEVER get anywhere near published EPA numbers. EPA might as well create a full weight WOT one mile MPG test just to show worst case numbers. Every vehicle I've owned and rented has grossly exceeded the EPA numbers if you drive properly. Also the people complaining failed to do sufficient research before purchasing the vehicle. They are probably the same class of people that sign contracts without reading them (obviously). Thirty seconds on Fuelly will give you a real world MPG number for the car of interest. Bottom line, don't trust the corporations, and even more-so don't trust the government. Do your own homework people!
      mikeeeemikek
      • 2 Years Ago
      Why do we need this government agency ???? with a $813 Million budget
        Gordon Chen
        • 2 Years Ago
        @mikeeeemikek
        The EPA also does air and water, among many other things.
        Bruce Lee
        • 2 Years Ago
        @mikeeeemikek
        Yeah we should get rid of it so absolutely nobody checks the fuel economy numbers that the manufacturers make up, absolutely nobody makes sure that factories aren't dumping toxic waste in the rivers, etc. Because obviously if we just let the manufacturers come up with their own fuel economy numbers they'd be super believable.
        peter_nixon
        • 2 Years Ago
        @mikeeeemikek
        You got THAT right. the EPA has been DISASTROUS. It must go. Don't forget to vote for Romney, if you have not already.
          Smith Jim
          • 2 Years Ago
          @peter_nixon
          Republicans sincerely believe If the environment is legitimately raped the Earth has ways to reject pollution.
          dravois
          • 2 Years Ago
          @peter_nixon
          Get lost.
          yomama6503
          • 2 Years Ago
          @peter_nixon
          Conservatard.
      JakeY
      • 2 Years Ago
      The article says: Friedland said that the tests are inaccurate enough that the EPA needs to have a "fudge" factor, "which further reduces the combined mileage by a factor of .7 to make the data better match the real world." That's no longer true since the 2012-2013 model year transition which required all new cars to do the actual 5 cycle test. Automakers are no longer allowed to do a 2 cycle test and apply a .7 fudge factor.
      Spec
      • 2 Years Ago
      Well, we can always trust the free market to self-regulate itself, right?
      Kris O.
      • 2 Years Ago
      So wait, it that max acceleration number just the max or is it the higher of full throttle vs the max test number? I can see accelerating slowly making a huge difference in these short test cycles.
        wilkegm
        • 2 Years Ago
        @Kris O.
        The test is driven by fiollowing a "trace". this trace calls for acceleration. The US06 trace used in the "high speed" test calls for greater acceleration. If a vehicle cannot match this acceleration, you just drive at WOT until you catch up to the trace.
      Typesbad
      • 2 Years Ago
      If the test is all on a dyno, how are the vehicle's aerodynamics taken into account?
        davethekoz
        • 2 Years Ago
        @Typesbad
        They use electrically controlled dynamometers for testing. The dynos have the ability to vary their resistance as a function of speed; so they can reproduce real-world roadload very closely (these are way more advanced than 'performance shop' or 'tuner shop' dynos). This is one aspect of fuel economy testing that is actually done according to an SAE procedures (J2263 specifies how to measure the roadload of the vehicle on the road, J2264 specifies how the dyno can reproduce that same road load in the lab)
        Kris O.
        • 2 Years Ago
        @Typesbad
        EPA site says drag is added to the dyno to account for wind resistance
        montoym
        • 2 Years Ago
        @Typesbad
        I'd imagine the .7 "fudge factor" might take some of that into account.
        Austin Too
        • 2 Years Ago
        @Typesbad
        There are two major factors used to adjust the resistance in the dynamometer rollers: 1. Weight -- Vehicles are weighed with a "loading" of all options over 33% installation rate. The measured weight then fits within a band (Inertia Weight Test Class). There can, therfore, be differences in fuel economy between a vehicle that is heavy in the weight class and one that is lighter (IIRC, the weight clasess are 125 pound bands) 2. Coastdown. Vehicles are allowed to coast down from a specific speed to a full stop. This test measures aerodynamics, tire rolling resistance, and other friction factors including bearings and fluids. There is some reporting I have seen in the Detroit Free Press that indicates that the Hyundai/Kia issue has to do with coastdown; specifically the tires.
          flychinook
          • 2 Years Ago
          @Austin Too
          Coasting on a dyno still doesn't take aerodynamics into consideration...
      SVX pearlie
      • 2 Years Ago
      This is not actually news, or at least, it shouldn't be news to anyone who paid attention to how EPA mileage ratings are created and presented. In some ways, it'd be better if mileage rating were left to SAE to standardize. I'd be much happier with SAE-certified mileage ratings than EPA-estimated.
        truewhiteboy
        • 2 Years Ago
        @SVX pearlie
        Consider it more of a Public Service Announcement. It's good information to have, not everyone knows it.
        Naturenut99
        • 2 Years Ago
        @SVX pearlie
        re:"I'd be much happier with SAE-certified mileage ratings than EPA-estimated." The amount of time it takes them to finalize things, we would get the mpg numbers after the vehicle was discontinued. Which is why the EPA doesn't test every vehicle every year... It is was too intensive a project to test every car every year (model version).
      Pandabear
      • 2 Years Ago
      6mpg off is not an "Honest Mistake", even a high school dropout would have caught that at the pump.
        rlog100
        • 2 Years Ago
        @Pandabear
        Also, a 'honest mistake' isn't made on most of your cars either. Let's blame the process for their false claims? Umm... No. Let's blame the process for allowing these two to get away with their false claims for so long and on such a scale.
        Spec
        • 2 Years Ago
        @Pandabear
        And if they were really 'honest mistakes' then half of them should be higher MPG and half of them should be lower MPG, right?
      • 7 Months Ago
      It seems like the EPA needs to tighten up their regulations and make the test much longer, you can't get accurate results for something that will drive hundreds of thousands of miles from such short tests. They should have a test where they run the car from a full tank to empty in the real world rather than in a lab.
      Rotation
      • 2 Years Ago
      You shouldn't have to learn how to drive it for highest mpg. Every car is tested by the same throttle inputs, hybrid or no. Also insideline (Edmunds) reports low mpg on their Fusion hybrid and Automotive News reports low mpg on their C-Max hybrid too. Driving at higher speeds will reduce mpg, but the effect of hybrid drive should be minimal at any steady-state speed. If the car doesn't have a plug, it gets all its energy from gas no matter what. Taking the energy from the engine through a generator, power conversion and motor isn't going to be more efficient than just using a driveshaft. You do realize that 66mph thing came from Ford, right? Do you think Ford is trying to inform or provide PR?
    • Load More Comments