EPA Overhauls Fuel Economy Estimates for 2008

Testing methods changed to mirror "real world" driving habits
By Philip Reed and Dan Edmunds , Director of Vehicle Testing
Date Posted 01-02-2007

As the 2008 model-year cars hit the lot, shoppers will notice a big difference — the EPA has changed its fuel economy testing methods to produce mileage estimates that reflect "real world" driving habits. The new testing process will significantly reduce estimated fuel economy — in some cases up to 25 percent.

The new EPA estimates for city and highway mileage will be listed on the window sticker of all 2008 model-year vehicles. The first day that 2008 models hit showrooms is January 2, 2007.

The previous EPA estimates were often criticized for being overly optimistic because they were based on the driving habits of the 1970s. The system was revised once, in 1985, but hasn't been adjusted since the 55 mph national speed limit was ended in 1987.

The new EPA fuel economy regulations consist of the following three elements:


Revised testing procedures to more accurately reflect today's traffic conditions, driving habits and vehicle usage.
New labeling for window stickers to provide more information that is easier to understand.
The inclusion of SUVs and vans with between 8,500 and 10,000 pounds gross vehicle weight rating (GVWR) in the testing process.
Here is a closer look at the changes to the EPA fuel economy regulations.

Revised testing procedures
The EPA has determined that changes to the testing procedure will produce fuel economy estimates that more accurately match what consumers will actually experience. The agency has also determined that important factors are missing from the current tests. Consequently, the new tests will include:

Testing at higher speeds (up to 80 mph). Previously, speeds were limited to 55 mph to match the speed limit of the 1970s.
More aggressive acceleration and deceleration (up to 8 mph per second rather than just 3.3 mph per second). The previous tests did not match today's hectic traffic patterns.
Hot-weather testing and measuring vehicle fuel economy while using the vehicle's air conditioner.
Testing in cold-weather temperatures while the vehicle's heater and defroster are operating.
Drivers will quickly notice a big difference between the fuel economy estimates using the testing methods prior to 2008 and the new testing methods.

City ratings will drop by an average of 12 percent. The fuel economy estimates of hybrid vehicles and other vehicles designed for high fuel economy might drop up to 30 percent of their existing rating.
Highway ratings will drop by an average of 8 percent while hybrids and other specialized fuel economy vehicles might be reduced by up to 25 percent.

Part II

New fuel economy labeling system
The window sticker for 2008 and newer models will include the following changes:

- The new fuel economy ratings will be displayed in larger type.
- Until June 1, 2007, EPA ratings earned under the old system can be displayed, too, but only in fine print that is not bold.
- For all of 2008 and 2009 model years, the statement "These estimates reflect new EPA methods beginning with 2008 models," can be written across the top of the label. The two-year period reflects the maximum time that 2007 and 2008 vehicles (old and new methods) might sit on the same car lot at the same time.
- The phrase "EPA Fuel Economy Estimates" will appear in large type at the very top of the label, clarifying for the consumer that these are government ratings, which may increase their credibility. It could also take the heat off manufacturers, who are often wrongly accused by consumers of overly optimistic estimates.
- Estimated annual fuel costs will be prominently displayed, based on 15,000 miles per year, $2.80 per gallon fuel, and the combined fuel economy (the formula assumes a city/highway split of 55/45 percent). If a manufacturer recommends or requires premium, the fuel cost will be calculated accordingly.
- A slider representing the fuel economy continuum, showing the upper and lower limits of a vehicle class, along with a triangle showing where the vehicle in question fits on this continuum, is added.
- The vehicle classes needed to make segment comparisons have been expanded, as minivans and SUVs now get their own categories, instead of the former "multipurpose vehicle" all-in-one category.
- "Your actual mileage will vary" statement is added, with added verbiage stating "depending on how you drive and maintain your vehicle."

SUV and vans (8,500 to 10,000 pounds GVWR) now included
For the first time, SUVs and vans between 8,500 and 10,000 pounds GVWR will have mileage estimates. Previously, all vehicles over 8,500 pounds GVWR were exempted from fuel economy testing and labeling requirements.

- These Medium-Duty Passenger Vehicles (MDPV) will become a newly defined class of vehicles.
- This will include the Ford Expedition EL, the Chevrolet Suburban and large vans

Part III

Fuel economy test history
In the 1960s, emissions testing programs began using a city loop in the Los Angeles basin. The 11-mile test was later standardized to run on an indoor dynamometer, a machine for measuring horsepower, torque and other engine dynamics. The so-called Federal Test Procedure (FTP) was adopted by the EPA for the fuel economy ratings program that began in the '70s.

The FTP 11-mile loop, with an average speed of 21 mph and top speed of 56, was used to provide the first "city" mpg ratings. In 1974, a Highway Fuel Economy Test (HFET) was developed to measure highway fuel economy. This 10-mile loop was also performed indoors on a dynamometer with an average speed of 49 mph and top speed of 60 mph, in recognition of the fact that people often exceeded the current 55 mph national speed limit.

Together, the FTP and HFET formed the basis for the initial fuel economy labeling program.

In the early 1980s pressure began to build for a revamp of the system, because the ratings were found to be outdated. The complaints were that test speeds were too low, the dynamometer test doesn't account for temperature and no air conditioner data was collected.

In 1984, a new rule applicable to 1985 and later vehicles was adopted. No changes were made to the FTP and HFET tests themselves, as doing that would cause problems for the entrenched emissions testing protocol. Instead, the fuel economy ratings were given a "downward adjustment." FTP city results were reduced by 10 percent to determine the new city rating. The new highway ratings were determined by a 22-percent reduction in HFET results.

Those changes worked well at the time, when speed limits were still 55 mph. But this system is still in place until the end of the 2007 model year.

Mounting complaints about the adjusted fuel economy figures system cited a number of problems:

- Test speeds are too low. The speed limit hasn't been 55 mph for decades and the 1985 adjustment isn't enough.
- Test temperatures of 75 degrees don't reflect temperature fluctuations that occur in most areas of the country.
- The air conditioner or heater/defroster isn't used in any of the test vehicles, which would consume more fuel.
- The speed at which the test vehicles accelerated and decelerated was way too low.

Part IV

Hybrid fuel economy will drop
In general, in order to get the highest window sticker possible, ultrahigh fuel economy vehicles like hybrids have, more than any other class of vehicle, been developed and tuned around the idea of doing well on the FTP and HFET test cycles. Reports from consumers that hybrids don't get anything close to the label values are an illustration of how unrealistic the outgoing tests have been, and illustrate the need for a realistic test method since manufacturers will "teach to the test" as much as they can.

Why will the new testing system affect hybrid vehicles so severely? There are several reasons:

- The abnormally low deceleration rates of the old test, just 3.3 mph per second, overemphasized the benefits of "regenerative braking" (turning braking into electrical energy stored in batteries) and unrealistically boosted fuel economy.
- Not including the effect of the air conditioner in the former test unfairly inflated fuel economy estimates as compared with non-hybrid vehicles.
- Lower speeds increased the electric-only operation time of hybrids since the gas engine is needed more at higher speeds. The higher speeds of the new test will offset this advantage.

What this means for car shoppers
Fuel economy labeling is good for comparative shopping, one of the goals for the EPA testing program. However, it is less valuable if the estimates do not accurately reflect the mileage folks are actually getting in their own vehicles.

It is important for shoppers to understand that new testing methods are in use in the 2008 model year. If not, consumers could find themselves comparing 2007 and 2008 vehicles without realizing that the fuel economy figures are very different.

If both 2008 and a 2007 model-year cars are on your shopping list keep in mind that the fuel economy ratings can't be directly compared. The 2008 car will appear to get lower city and highway mileages. The city mileage will be about 12 percent lower than the 2007 estimate while the highway mileage will be approximately 8 percent lower than the 2007 estimate.

For more information and resources check this: http://www.mileagewillvary.com/flash.html.

It is also important for shoppers to realize that even the 2008 mile estimates are only that

Interesting stuff. I would have expected an adjustment in the other direction, though, considering how many 4Runner owners report getting better mileage than the current EPA estimates.

Will the EPA use winter blend or summer blend fuel? In my past vehicle, winter blend seems to knock off 3 MPG vs. summer blend.

So basically it's 8/12% drop for city/highway conditions.
Does it means that 4Runner consumption will be:

Engine........City/Highway
.................Old.............New

V6...........17/21...........15/18.........MPG
............13.5/10.2......14.6/11.4......L/100km

V8...........16/19...........14/16.........MPG
............14.6/11.3......15.8/12.7......L/100km

Thanks to Koz, here is a link to the new ratings for all vehicles: http://www.fueleconomy.gov/feg/sbs.htm

This is hilarious. All of a sudden people aren't going to be so excited about hybrids. Car makers should practically be sued for misrepresenting the gas mileage by 30% on hybrids.

I doubt any automaker could be successfully sued if they could show they were in reasonable compliance with previous existing government standards.