Subaru Introduces 40MPG Turbo Parallel Hybrid Concept
TRW Introduces Portfolio of Products for Hybrids

EPA Proposes New Methods for Estimating Fuel Economy

One of four proposed new fuel economy labels

The EPA today proposed new rule and test methods for calculating fuel economy estimates, as well as four options for a new design of the fuel economy label that will provide a more quantitative view of “your mileage may vary.”

EPA’s goal is to bring the MPG estimates closer to the fuel economy consumers actually achieve on the road. The new MPG estimates will take effect with model year 2008 vehicles, which will be available in dealer showrooms in the fall of 2007.

Currently, mileage estimates come from data from two laboratory tests which were last revised in 1985. At that time, the fuel economy figures derived from those test were adjusted downward—10% for city and 22% for highway—to more accurately reflect driving styles and conditions.

Current test are run under mild temperatures without the use of accessories such as air conditioning, and with sedate acceleration and speeds capped at 60 mph.

That’s not the case for emissions tests, which have been enhanced since the mid-1990s to require the use of a much broader range of real-world driving conditions, such as high-speed, fast-acceleration driving and the use of air conditioning and colder temperature operation (20º F).

These conditions and behaviors not only affect the amount of emissions, they also have a significant impact on fuel economy.

EPA is proposing the incorporation of those tests into the methods used to determine the fuel economy estimates posted on the window stickers of new cars and light trucks. EPA is also proposing that the fuel economy estimates reflect other conditions such as road grade, wind, tire pressure, load, and the effects of different fuel properties.

In 2011, another provision would require manufacturers to perform additional cold temperature, air conditioning and/or high speed/rapid acceleration driving tests for some vehicles that may be more sensitive to these conditions.

The fuel economy for each vehicle model would continue to be presented to consumers as city and highway MPG estimates.

Under the new methods, fuel economy ratings will drop for most vehicles. EPA estimates conventional (non-hybrid) vehicles would drop on average by about 10–20% from today’s labels, while the highway estimates would drop by about 5–15%, depending on the vehicle.

For hybrid vehicles, the city MPG estimates would drop 20–30% from today’s labels. For highway MPG estimates, the change is about the same as for conventional vehicles. 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.

EPA is providing sixty (60) days for the public to submit written comments on this proposal, including comments on the proposed label designs.




I'm surprised there haven't been howls of outrage from Detroit denouncing this as effectively a backdoor CAFE increase. Which of course it is, isn't it?

John Allison

Backdoor CAFE? Not really. This looks to be a response to consumers demanding proper mileage estimates from those EPA stickers. Providing more accurate data points will allow for a better comparision of all of the different types of hybrid technologies emerging from the auto industry.

Will this also affect CAFE? Probably, but this does not look like a conspiracy to thwart Detroit.


Hey John,

I don't mean that it's (necessarily) *intended* as a way of boosting CAFE, just that it will have that effect. Which I'm pretty sure it will, since IIRC the EPA mileage numbers are the basis for CAFE.


No howls of protest because the point is moot. The rising cost of gasoline will impose market pressure on Detroit to raise the fuel economy of its fleet to stay in business. If Ford and GM thought oil was going to drop back down to $30 a barrel, then you'd hear howls of protest. (Or maybe not, because if that were the case no one would care about whether or not EPA estimates were accurate to begin with.)


CAFE standards will still be based on the old test methods. They know they can't get away with a backdoor increase.


Actauly as likely as not big cars will do better under the new system then the old. I know our old van always got better milage then its sticker said and I know alot of big cars that actauly get fairly good milage. I also know alot of supposedly great milage small cars that in realty suck ass.

Dave Zeller

The whole issue of EPA fuel economy ratings has been based upon test speeds that the auto industry considers "typical" for an owner of one of their cars; however, this has been taken advantage of by some manufacturers to "boost" their fuel economy ratings.

For example, Ford products are tested at highway speeds typical of what one generally sees on the interstates today; i.e., a driver who is running at 75 to 80 m.p.h.
I have a Mercury Grand Marquis which will achieve its rated economy of 25 m.p.g. at those speeds; if I slow down to 70 m.p.h. it will get 27 m.p.g., so on and so forth. Basically this huge V8 car gets the same fuel economy as the much smaller Asian V6 luxury compacts.

I believe some of the Toyota vehicles are the worst offenders, as they consider a proper interstate highway speed to be around 55 m.p.h. This has much to do with the poorer fuel economy that their hybrid owners have been reporting as of late.

Wayne Gerdes

Hi All:

___It will not affect CAFÉ directly given the way the new FE estimates are structured but it will affect purchasing habits of the average American consumer. When said average consumer sees the Chevrolet Suburban, Dodge Durango, Ford Expedition, and Toyota Land Cruiser w/ newly revised 2008 EPA estimates of 8, 9, or 10 mpg city while gasoline costs $3.20 or more per gallon, I think even the most brain dead consumer will wake up out of their coma and pay heed …

___Good Luck

___Wayne R. Gerdes


I beat the EPA estimates in all the cars I have owned.
96 Integra GSR 25/31 I got 30.7
97 Civic EX 32/36 I get 36.2
01 Toyota MR2 25/30 I get 31.7

I drive 60% hiway usually around 65mph. I don't know what everyone is complaining about.


I think that the change and the proposed EPA graphic is great. I wish they could get it in place sooner. Bring it on EPA.

tom deplume

One thing the EPA doesn't factor in is how much time is spent in traffic jams with the engines idling and getting zero mpg. This is a situation where even mild hybrids would advantageous.


A lot of the city test involves idle time, and that's why the hybrids with automatic engine shutdown have such large city numbers, and why normal cars have worse city MPG than highway.


A lot of the city test involves idle time, and that's why the hybrids with automatic engine shutdown have such large city numbers, and why normal cars have worse city MPG than highway.

hampden wireless

The CNBC business show said it WAS a backdoor cafe increase. Not a big one though but something is better then nothing. The report could have been wrong.

Rafael Seidl

The CAFE program is administered by the Dept. of Transportation, based on numbers generated by the EPA using certain standardized tests. The *additional* tests EPA is now (finally) proposing relate to aggressive acceleration, the use of air conditioning and more. Together with the old tests, these will allow EPA to provide consumers in the market for a new vehicle with more accurate estimates of real-world MPG.

However, the additional tests are not (yet ;^) to be included in the computation of the MPG numbers used for the purposes of CAFE and the gas guzzler tax:

Since this would yield two sets of official MPG numbers, it is unclear which one carmakers will be allowed to advertise with. Consumers could end up seriously confused and demand that the current - more lenient - way of computing MPG be scrapped altogether. The CAFE targets and gas guzzler thresholds could then stay the same but become harder for carmakers to achieve. On the other hand, with GM and Ford already on the ropes, I suppose Congress is likely to resist all changes that might hurt their bottom line - especially in an election year.

The comments to this entry are closed.