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Energy
Fuel economies, Part II

With rising gas prices, fuel economy is becoming a more important factor in people’s decision to buy a car, as discussed in part I of this series last month. Hybrid vehicles are thus becoming more appealing, yet even hybrids do not get the gas mileage listed on manufacturers’ window stickers. In a recent J.D. Power and Associates survey, hybrid buyers listed “excessive fuel consumption” as a top complaint against the alternative vehicles. In response, a number of car companies are joining consumer and environmental groups in calling for an overhaul of the fuel-economy tests performed on new cars to calculate mileage per gallon.

Each year, the Environmental Protection Agency (EPA) publishes a fuel-economy guide that lists the fuel efficiencies of new passenger vehicles. When new cars hit the lot, federal law mandates that labels on the windows represent the gas mileage achieved in the EPA tests, which were designed in the mid-1970s. The fuel economy listings are a weighted average of two laboratory tests for city and highway performance and are designed to be a basis for comparison between cars, says John Millet, an EPA spokesman.

The city test is an 11-mile-long, stop-and-go test where the average speed is 20 miles per hour. The highway test is 10 miles long with an average speed of 48 miles per hour, no stops and very little idling. In 1985, at the urging of consumers, EPA conducted a study and determined that drivers in actual conditions were getting 90 percent of EPA’s city values for mileage and 78 percent of EPA’s highway values. Since then, when calculating fuel efficiency on the sticker, they have adjusted the test results down by 10 percent for city mileage and 22 percent for highway mileage.

But that adjustment still is not enough, according to a petition filed two years ago by Bluewater Network, an environmental watchdog, to persuade EPA to reassess its testing standards. Bluewater Network states that average fuel economy is as much as 34 percent lower than the tests suggest, leaving at least a 10 percent gap between the already adjusted values and what people are actually getting. The problem, Bluewater suggests in the petition, is that the test procedures and calculation methods were designed nearly three decades ago, “when conditions on America’s roads were far different than they are today.”

Many things have changed over the years since EPA designed the tests, says Toyota, which has joined in the request that EPA revise its tests. Speed limits have increased, but the highway tests average at 48 miles per hour and top out at 60 miles per hour. Congestion has increased three to four times since 1982, according to the Texas Transportation Institute, and much more time is spent in stop-and-go driving than is considered in the tests. The EPA tests do not account for the use of air conditioning, yet 99 percent of all vehicles have it. Other complaints about the EPA tests include driver habits that have changed, such as aggressive driving and quick acceleration and braking — the tests assume very gentle acceleration and braking.

“Our goal is to put the most credible information possible on a car,” EPA’s Millet says, and Bluewater Network “has made a strong case that our methodology is outdated.” Recognizing this problem, EPA is currently reviewing its testing procedures and calculation methods and should come to a decision in the next year about whether or not changes need to be made, Millet says. Consumers need to keep in mind, he says, that these tests are estimates, and there is no way to eliminate all variability.

Toyota says that its Prius hybrid owners routinely get more than 45 miles per gallon, which is more than double the national average for passenger vehicles. However, the EPA tests suggest owners should get 55 miles per gallon on average. Nonetheless, hybrids in general tend to get more than double the national average, and J.D. Power says that fact will lead to an increase in sales of hybrids, as gas prices continue to rise.

Megan Sever

Read the first part of this series: "Fuel economies, Part I," Geotimes, October 2004.

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