While Senate Republicans complained that the bill does nothing to increase domestic oil production, Democrats said that's because the nation must move energy policy away from its heavy reliance on oil.
The House is preparing its own version.
The Senate bill requires automakers to increase fuel economy to 35 miles per gallon, about a 40 percent increase over what cars, SUVs and small trucks are required to achieve now. It would lump all the vehicles under a single regulation, but also give manufacturers flexibility so large SUVs wouldn't have to meet the same requirements as smaller cars.
It requires a yearly increase of ethanol production to 36 billion gallons a year by 2022, a sevenfold increase from today. By 2015 half of the new vehicles offered to buyers _ as many as 10 million _ will have to be capable of running on 85 percent ethanol, biodiesel or some other alternative energy source.
And for the first time, the president must find ways to cut oil demand by 20 percent of what it is expected to be in 2017 _ a target President Bush has embraced _ and attain further reductions after that. Gasoline demand is expected to grow 13 percent to 261 billion gallons a year by 2017 without some fuel saving measures.
But will auto showrooms provide the same selection of vehicles? Will they be as big, as powerful, as safe?
"I would expect them to look a lot like they do today, the same size, the same acceleration and the same or even better safety," says David Friedman, director of the clean vehicles program at the Union of Concerned Scientists.
He maintains they will have better technology, better engines, more efficient transmissions and stronger aluminum bodies. They'll cost a little more but use much less gasoline.
"The goal is to replace fossil fuels with alternative fuels and use conservation," said Sen. Maria Cantwell, D-Wash., who was involved in the discussions on many of the auto fuel economy and motor fuel issues that ended up in the bill.
What has changed from a few years ago, she said, is there no longer is "a fear factor that you're going to be in itty bitty cars" if the government requires automakers to make more fuel efficient vehicles.
In addition to making conventional cars more fuel efficient, the bill seeks to boost research into use of lithium-ion batteries _ like those used in laptop computers and cameras _ in vehicles.