More than 31 million travelers are expected to hit the nation’s highways this Memorial Day weekend, none of them wanting to spend more money than they must at the gas station.
Many of those drivers won’t see the fuel efficiency promised when they bought their vehicles, say several consumer and environmental groups.
The government’s method to calculate fuel economy is 30 years old, and does not consider today’s busier highways, higher speed limits and increased use of air conditioning.
So the Environmental Protection Agency is re-evaluating the way it calculates fuel efficiency to make sticker information on new vehicles more reliable.
“We believe consumers should have the most accurate information possible when it comes to expected gas mileage of the vehicles they purchase,” Susan Pikrallidas, vice president of public affairs for AAA, said in a statement. “This would be accomplished by requiring EPA to use real-world tests in setting federal mileage estimates.”
The Senate passed a highway funding bill in May that contains a provision requiring the EPA to make its fuel economy tests more realistic. The process already was under way, said agency spokesman John Millett, and it will continue regardless of whether President George W. Bush signs the bill.
“We have a lot of data to look at, and from analyzing that data, we hope we can make appropriate changes to make the window stickers more accurate,” Millett said.
The automobile association says its own tests show the stickers could be off by as much as 30 percent on some models.
Manufacturers currently are required by the agency to test new models for fuel efficiency on treadmill-like machines called dynamometers inside their own test labs.
Professional drivers take the models through 30-year-old driving cycles resembling city and highway conditions. The cycles are standardized and designed by the EPA. The agency confirms about 10 percent to 15 percent of the manufacturers’ calculations inside its own lab in Ann Arbor, Mich.
Because the tests are conducted in a controlled environment, they don’t account for many factors drivers encounter daily, such as weather, driving with the windows down and using the gas-consuming air conditioner.
The highway test is a 10-mile drive at an average speed of 48 mph. Unlike rush-hour in a large city, there is little idling and no stops. The test simulating city driving is about 11 miles with 23 stops, with 20 mph as the average speed.
A lot has changed since the driving cycles were designed in the 1970s: Congestion is worse, highway speed limits are higher and most automobiles now have air conditioning.
“That’s part of what we’re looking at now,” Millett said.
In March, AAA published a list of 39 vehicles that its testers put through a range of driving conditions, including stop-and-go traffic, steep grades, trips to the supermarket and a mix of highway and city driving.
The organization’s tests were neither standardized nor scientific, AAA said, but reflect more realistic fuel use. The 2003 Toyota Tundra, for example, got 12.9 miles per gallon in the AAA test, verses the 14 to 17 miles per gallon listed on the fuel sticker.
Some say the arguments from consumer and environmental groups are exaggerated and that the current fuel stickers give motorists an accurate enough number on which to base a purchasing decision.
The EPA expects to propose changes this year. The Association of International Automobile Manufacturers, based in Washington, supports the federal effort to re-evaluate testing procedures but is concerned that new rules might expand testing burdens on the manufacturers.
No test can be typical of most driving conditions, said John Cabaniss, the director of environment and energy for the manufacturers’ group. Traffic conditions change constantly and all highways and city streets are different.
“You have to have a standard cycle to do these things, but any cycle you pick is not going to be typical of every city,” he said. “The best you’ll ever be able to do is compromise.”