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MotorWeek Video Transcript: EPA's 2008 Fuel Economy Tests

John Davis: Nothing is more frustrating for a new car owner than finding that the fuel economy estimates found on the window sticker just don't match up with the mileage they get in real-world driving. Now this has been especially true of the new hybrid cars and trucks. Well, the folks at the EPA, who test new vehicles to and are now phasing in a new, more accurate method for estimating fuel economy. So we've asked our FYI reporter Yolanda Vazquez to fill us in on what’s behind the new numbers.

Yolanda Vazquez: If you're shopping for a new car this summer, don't be surprised if you see two seemingly identical cars with different fuel economy ratings on their window stickers. For 2008, the EPA is revising the way it determines its economy figures, and the Department of Energy is working to make sure the info is easy to find and understand. Under the new system, most cars will carry a significantly lower number than before.

Dr. David Greene, Oak Ridge National Lab: Consumers will begin to see cars with new, lower fuel economy estimates on the same lot with cars with the old, higher fuel economy estimates. I think it's going to create some confusion for awhile.

Vazquez: You see, the fuel economy estimates found on 2007 and older cars were determined using test procedures that were developed when this car was new and the driving environment was much different from today.

Amber Kittner: The figures they use on it now are really old from what they say—really old data.

Vazquez: Do you know how old it was?

Kittner: 15 or 20 years—something like that.

Vazquez: Back from the 60s and 70s.

Kittner: Wow, see that's way out of date.

Dr. Greene: The old tests are now more than 40 years old, based on driving that doesn't include high-speed highway driving, doesn't include the kind of rapid acceleration that modern vehicles are capable of, and doesn't include as much use of air conditioners or accessory equipment as we now have on automobiles.

Vazquez: The test itself is run on a chassis dynamometer in a controlled laboratory environment. The test cycle driver follows a pre-programmed “route” that approximates stops and starts in an urban environment, idling time, and free-flowing traffic at up to 60 miles-per-hour.

The raw economy numbers from these tests are used in determining a car makers compliance with Federal CAFE standards, but the number found on the window sticker is determined by applying a pre-set multiplier, to account for variables such as wind, temperature and driving conditions that can lower fuel economy.

For the past few years, though, the EPA has been re-thinking this procedure, trying to get estimates that are more consistently closer to real-world driving results.

Donn Weinberg: As long as they feel it's going to more accurately reflect what people will to get and if in fact they are going to take into account there are many aggressive drivers, so much the better.

Vazquez: So beginning with 2008 model-year cars, the EPA is including results from three additional test cycles in their calculations: One that includes more aggressive acceleration and highway speeds up to 80 miles-per-hour, another with the use of air conditioning, and finally a 20-degree cold start.

Of course, the reason for providing fuel economy estimates is so car buyers can choose the most efficient vehicle that meets their needs, so the window stickers themselves are also changing with the times.

Beth Petry: I hope they're a realistic estimate because with gas prices being what they are, we really need to start paying more attention. I know my next vehicle is getting ready to be purchased and I'm going to take a closer look.

Vazquez: To find more information on how the new tests work and how your car stacks up, you can visit the DOE's fuel economy website.

Dr. Greene: We will have the new fuel economy numbers for every car, even estimates for used cars going back to 1985, so we will be revising all of the cars fuel economy estimates to be consistent with the new measurement system. They can also bring up any car and look side-by-side at the new and the old ratings and see how they've changed.

Vazquez: As with anything new, the revised fuel economy estimates will take a little getting used to, and remember that mileage will still vary based on driving behaviors and road conditions, but consumers can feel confident knowing that what you see on the window sticker should now hold true on the roads as well.