Gaming The EPA Gas-Mileage Tests: Well, Europeans Are Worse...

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A few recent, high-profile cases have brought fuel economy testing procedure into question.

When Kia and Hyundai are being sued for inaccuracies in reported EPA figures and Ford hybrid drivers are missing out on official numbers by 20 percent, suggesting the designs of some vehicles may enable them to pass tests without that efficiency making it all the way to the road.

Still, it could be worse--you could be European, where some carmakers are really cheating the tests.

The Guardian (via Autoblog Green), says that some carmakers are over-inflating tires, taping up gaps and adjusting brakes for less resistance to boost their official figures. This results in misleading fuel figures for the customer, and artificially bumps some cars into lower CO2-based tax brackets, a major factor for European car sales.

While there are some impressively efficient cars sold in Europe--and significantly more to choose from than in the U.S.--the discrepancy between quoted and real-world figures can often be huge.

In the UK, drivers are achieving 87 percent of the official figures on average--not too bad, considering we usually suggest a 15-20 percent discrepancy between EU and EPA numbers, car-for-car.

But some are as low as 70 percent or less, often at the most economical end of the scale--small-capacity turbocharged units, for example. These are cars essentially designed to ace the tests thanks to optimized gearing or fuel mapping--but they don't work so well in normal driving conditions.

The additional cheats being used in testing can put those figures even further out of step--as most drivers don't pump up their tires, or tape up panel gaps to boost economy.

Irritatingly for many, the carmakers aren't even breaking any rules. According to Transport And Environment, who carried out the research, "There is no evidence that carmakers are breaking any formal rules--but they don't need to--the current test procedures are so lax there is ample opportunity to massage the test results."

Even prior to some of these cheats being discovered, there have been several calls for the testing procedure to be altered to give more realistic real-world numbers.

The current test includes an "urban" figure derived from only 2.5 miles of driving after a cold start; an "extra-urban" number over 4.3 miles of higher speeds--a maximum of 75 mph, an average of 39 mph--and an "average" of the other two, weighted by distance. Gear-changes are made at predetermined points (in manual vehicles), and all tests have the same starting, stopping and idling times.

A full exposé on the procedure can be found in Transport And Environment's pdf document.


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Comments (7)
  1. Thanks for the reporting on this issue. I hope that public pressure causes revised procedures and more realistic numbers. All the cars should be similarly tested under procedures that are as realistic as possible (within limits of course).

  2. It is a test, so company will figure out a way to "game" it.

    So, the test needs to be a constantly improved...

  3. Yes, sounds like it needs more monitoring against cheating simple as that.
    Regardless of the outcome though figures produced will always be unobtainable by some drivers. The difficulty is convincing them they are to blame and not the system or car maker.

  4. Antony the reason the small capacity turbo cars don't get the economy is the way they are driven. These cars are fun to drive and encourage aggressive use whether provoked by other road users or the driver alone. They will produce the economy but many drivers today haven't a clue to driving for economy especially with the performance fun factor lurking in the background.

  5. There's an element of truth to that Don, but it's not always the case. Some, particularly the smallest examples such as Ford's 1.0 Ecoboost and the Fiat TwinAir, are very, very difficult to extract good figures from - it's not simply a case of being gentle with them, but deliberately driving significantly slower - which rather negates the benefits of selling them as capable of matching the performance of larger-engined cars.

    There is an exception to this, though, and it's from a company which has turbocharged small engines for years - Smart. Even "hammering it", I've got better economy from a BRABUS Smart Fortwo than I have driving moderately in one of the others.

  6. The best way to solve this is through a well defined operating mode on all cars.

    Requires all automaker to comes up with an "EPA" mode (beside, sports, eco, normal, winter...etc). Once the car computer is in that mode, then it MUST produce the same MPG while operating on a well defined EPA course with EPA conditions... In that way, owners can easily verify the EPA mileage themselves...

    It should be easily done through computer controlled software...

    Of course, most owners will find that "EPA" ridiculous slow (except for few hybrid owners)...

  7. My personal preference is to come up with a usable city driving test, and then simply record economy at a variety of different speeds - say 50, 60 and 70.

    That should be enough data for most, and it'd let people know roughly what to expect when driving at their typical highway speed. And if you do 80 everywhere, it's easy enough to assume you'll probably get less than the 70 figure shows!

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