Though the technology exists to make cars and trucks more fuel-efficient, there is a potentially lethal downside.
According to a new study from the prestigious National Academy of Sciences, automobile fuel efficiency could improve over the next 10 to 15 years if manufacturers made lighter vehicles. But, suggests the report, lighter cars could potentially result in more traffic deaths.
SUV MPG Targeted
Among its findings, the study says automakers could boost the mileage of gas-guzzling sport utility vehicles, pickup trucks and passenger cars by up to 30 percent over the next decade. The report did not recommend any specific increases in the federal standard, deferring that decision to elected officials instead.
The federal corporate average fuel economy standard, or CAFE, currently requires cars to achieve 27.5 miles per gallon on a fleet average. Light trucks, a category that includes SUVs and minivans, must achieve a fleet average of 20.7 mpg.
The academy report said the federal CAFE rules, imposed after the oil embargo in the early 1970s, have been an effective tool in getting automakers to produce more efficient cars. This has saved an estimated 2.8 million barrels of oil a day, the panel estimated.
Lighter Cars Debated
But the panel also noted that the shift to smaller, more lightweight cars may have resulted in 1,300 to 2,600 additional traffic deaths. The academy panel noted that if fuel economy increases encouraged production of smaller and lighter cars, "some additional traffic fatalities would be expected."
However, those concerns could be reduced greatly if the weight and size reductions were focused on larger vehicles such as SUVs, minivans and pickup trucks.
"Larger vehicles would then be less damaging in crashes with all other vehicles and thus pose less risk to other drivers on the road," the panel said.
Cost Savings Seen
Many environmental groups support a raising of CAFE standards, noting that a short-term investment would reap longer-term benefits for consumers both in the amount they would spend on gas and in saving the environment.
"If the fuel economy standards were at 40 miles per gallon by 2012, in 2010, consumers would be saving close to $10 billion per year," says David Friedman, senior analyst with Union for Concerned Scientists. "The environmental impact of their driving would be greatly reduced."
But the auto industry said the NAS study left many tough questions as to how to achieve these savings unanswered.
"Automakers are committed to increasing fuel efficiency and we are increasing it every year, but this is a very complex issue and I think that the NAS report released today shows that," says Gloria Bergquist of the Alliance of Automobile Manufacturers in Washington.
White House Responds
The 200-page report won't be fully reviewed by the government for months. But the findings are expected to be important to a congressional debate that will take place in the House later this week.
Lawmakers are expected to debate whether to increase the fuel economy requirements for cars and sport utility vehicles as part of a broader energy bill on Wednesday.
While White House spokesman Ari Fleischer called the study "encouraging," but also pointed to the downsides that the study raises.
"It also takes into account the problems that are created with lighter vehicles, increased deaths on the road as a result of lighter vehicles," said Fleischer.
ABCNEWS' Ann Compton contributed to this report