Over the last two decades, auto engineers have developed hybrid engines, better transmission systems and countless other safe and affordable fuel-saving technologies. Yet the average vehicle sold in the United States today goes a mile less on each gallon of gas than it did in 1987.

Instead of prioritizing efficiency, however, domestic automakers focused on increasing weight and power, a choice they're paying for in lost profits and rising global warming pollution. They staked their future on large SUVs and trucks that are more prone to rollovers and less compatible with other cars, driving a 15-year increase in traffic deaths. And, claiming it was looking out for the Big Three, Congress neglected the fuel economy improvements that could have saved money, jobs and lives.

Back in 1975, in response to price shocks after Arab oil embargoes, lawmakers required auto manufacturers to double their fuel efficiency within a decade. According to the National Academy of Sciences, the nation saves 117 million gallons of gas each day as a result.

That original fuel economy law, however, set a weaker standard for SUVs, pickups and other "light trucks," which accounted for just 20 percent of the U.S. auto market at the time and were primarily used in agriculture and commerce. Taking advantage of this division, industry started churning out larger and less-efficient vehicles. Today, half the vehicles sold in the United States are "light trucks," and most of these gas-guzzlers are used no differently than passenger vehicles half their weight.

Yet whenever anyone proposes closing the light-truck loophole or raising fleetwide standards, they're met with a familiar chorus of opposition. First, critics claim that progress is too expensive, and the struggling U.S. auto industry cannot afford to comply with higher efficiency requirements.

If they look around, they'll see that Chrysler just let go of 16 percent of its North American workforce, Ford posted an unprecedented $12.6 billion loss in 2006 and the more mileage-conscious Toyota is poised to overtake GM as the nation's top seller. Rising oil prices hit SUV sales hard, and the Big Three were especially vulnerable. The predicted collapse is here, and our inaction on fuel economy deserves a large part of the blame.

Opponents of higher standards also claim increased mileage will force drivers into lighter and less-safe vehicles. This ignores the wide range of efficiency improvements that are possible without any downsizing, and significant research showing that structure and design have a greater impact on vehicle safety than weight does.

But the premise of this argument also is flawed, as it falsely assumes the trend toward bigger vehicles has made our roads safer. In fact, unlike Canada and much of Europe, traffic deaths are gradually increasing in the United States, partly because the larger size gap among vehicles has heightened the threat posed by collisions between light trucks and cars. When rollovers are factored in, the overall risk is similar for occupants of cars and SUVs, while well-designed cars like the Volkswagen Jetta provide better driver and passenger protection than much larger SUVs.

Finally, some lawmakers have tried to deflect attention from fuel economy proposals by downplaying their impact on global warming. The numbers suggest otherwise; transportation accounts for roughly one-third of our nation's carbon dioxide emissions, and most of that comes from cars and light trucks. Any plan to stabilize our climate needs to address this major source of pollution, and increased efficiency is the quickest and most effective way of doing so.

After decades of false starts, fuel economy proposals are already starting to move in Congress. Eliminating the light-truck loophole and raising fleet-wide standards would cut our dependence on foreign oil, reduce our contribution to global warming and improve highway safety.

Meanwhile, the arguments against action — including industry's doom and gloom — are nothing new. During the first fuel economy debate in the 1970s, Ford said that higher mileage stand-ards could require a "product line consisting...of all sub-Pinto-sized vehicles." Congress passed that bill anyway, and Ford's vision of subcompacts has given way to a much scarier reality.

Marc Ross, a professor emeritus of physics at the University of Michigan, has testified before Congress on automobile fuel efficiency and its safety impacts.