The Environmental Protection Agency (EPA) has long tested new cars annually for fuel economy. Current miles-per-gallon figures, however, are based on outdated driving habits and do not account for several features that impact the rate at which vehicles consume gas.
Under pressure from the Consumer's Union and the American Automobile Association, the EPA recently announced that by the end of the year it would make significant changes to methods used for estimating fuel economy ratings.
The EPA's fuel economy ratings are approximately 30 percent higher than the actual numbers, according the Union of Concerned Scientists.
The organization severely underestimates average driving speeds on the highway: the EPA assumes an average speed of 48 mph and a top speed of 60 mph, while many state highway limits are set at or above 65 mph.
Government data has shown that fuel economy can drop by 17 percent for modern vehicles that drive at 70 mph instead of 55 mph. Driving at 65 mph rather than 55 mph causes a ten percent drop in fuel economy. The current EPA guidelines also underestimate the amount of time spent in stop-and-go urban traffic and assume drivers accelerate and brake very gently.
The EPA does not account for the use of gas-dependent air conditioning, although 99 percent of cars sold in the United States today include air conditioners.
The EPA also overestimates trip lengths. Its city test cycle is 7.5 miles long, but according to the EPA's own data, average trip length is only five miles long. This difference between EPA testing conditions and the actual average length of driving trips is significant, since engines do not have time to heat up and do not operate efficiently during shorter trips.
As the EPA obtains more accurate fuel economy ratings, auto companies will need to produce more efficient vehicles in order to remain competitive and meet consumer needs.
More fuel-efficient technologies should help the consumer. According to the Union of Concerned Scientists, "a fleet of cars and light trucks that reaches 40 mpg [miles per gallon] will cost consumers only about $1,000 to $2,000 extra per vehicle." This increase in principal should pay for itself, as consumers would save an estimated $2,500 to $5,300 on fuel over the lifespan of the vehicle.
Americans could save an estimated $50 billion dollars worth of gasoline annually if all vehicles met the 40 mpg standard. The Union of Concerned Scientists estimates that owners of the 10 most fuel-consuming vehicles in the nation could save about $200 a year if their car's fuel economy was raised by 27 percent.
Ramsay Huntley, a Climate and Entrepreneurship Specialist with the Tufts Climate Initiative, said increasing fuel economy is an important goal, because of the many potential benefits. "Considering that average mileage has been trending down for a number of years, this could be quite significant and is a worthy pursuit, even if you're not considering the environmental benefits," he said.
Senior Chelsea Bardot owns a hybrid Honda that averages between 40 and 45 miles per gallon. "It's a great car, it's very easy to drive, and I never have any problems with it," Bardot said. "Especially now, considering the current gas prices, the investment definitely paid off."
The environmental solutions go far beyond gas mileage for vehicles. "Our society would be better off by increasing the energy efficiency of our buildings and by designing towns that are less dependent on the car in the first place," Huntley said.
