Envautomental

it can live with. The magic number is 35 mpg, and automakers have 13 years to get there. Now the question is: How?

Meeting that benchmark will require developing new technology, investing billions in new manufacturing and shunning the “bigger is better” mentality that has guided the auto industry for 20 years. It will be an unprecedented challenge and a seismic change for an industry that has never had much interest in either.

“This is the automotive equivalent of the moon shot,” Ron Cogan, the editor and publisher of and GreenCar.com, told us. “They know they have to reach these goals. They know it won”t be easy. They”ll have to marshal all of their resources, and those of their suppliers, to do this.”

A by researchers at the Massachusetts Institute of Technology found automakers could double fuel economy relatively easily by emphasizing lighter - though not necessarily smaller - cars with more efficient gasoline, diesel and hybrid drivetrains. And that, industry experts told us, is pretty much what the industry will do.

Just eight vehicles among the 2007 models get a of 35 mpg or better, and they”re all subcompacts or small hybrids. Automakers don”t have to make sure each vehicle they sell averages 35 mpg, they have to ensure the average of all their vehicles is 35 mpg.

Industry experts said the first changes will be relatively subtle, relatively cheap and relatively soon. They”ll include improved aerodynamics, six-speed automatic transmissions and replacing engine-driven components like power steering pumps with electric ones. The cumulative effect can be significant. Ford says these tactics boosted the fuel efficiency of the V-6 by 10 percent. Dual-clutch transmissions, more efficient gearing and tires with lower rolling resistance will bring further improvements.

Subcompacts are the of the market, but no one expects automakers, particularly in Detroit, to dump SUVs in favor of micro cars. But automakers will use a lot more aluminum, magnesium and lightweight steel to make vehicles lighter.

The most radical changes will come under the hood. Automakers will embrace direct injection — a more efficient means of getting fuel into the combustion chamber — in a big way and bring more diesel and hybrid drivetrains to market.

“We”re looking at massive changes in engine technology,” Aaron Bragman, an auto industry analyst with Global Insight, told us. “Two-thirds of the U.S. fleet will have to change to direct injection. One-third of the total market will be diesel, and half of those will be diesel-electric hybrids. Everyone is pursuing a strategy of smaller engines with direct injection and turbochargers.”

American automakers may face the biggest challenge, they may be in the best position to make quick gains, experts said, because of their deep product lines in Europe. Detroit is already making smaller and thriftier cars there. Companies just need to figure out how to adapt them to American regulations and sell them to American consumers.

General Motors is already figuring that out. Earlier this week, GM unveiled the Saturn Astra, a slightly reworked version of the Opel Astra, one of Europe”s best-selling compacts. Its 1.6-liter turbocharged engine delivers 32 mpg.

Many industry pundits said GM is leading the race to build cleaner, more fuel efficient cars and is most prepared to meet the new regulations. The company recently announced a sweeping campaign to improve the fuel efficiency of its entire product line while embracing hybrids and alternative fuels.

We”ll have more in a bit…

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