I don't know what the current situation is but this article describes the status in 2007.
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WASHINGTON -- As automakers face a key Senate vote on fuel economy regulations next week, lawmakers introduced a new bill Friday that could shrink sales of large vehicles.
The new bill targets a controversial tax incentive that allows small businesses to write off up to $25,000 of the purchase of the largest pickups and sport utility vehicles.
The sponsors, including U.S. Rep. Ed Markey, D-Mass., chairman of the House select committee on global warming, and Rep. Rahm Emanuel, D-Ill., head of the House Democratic caucus, said the bill would fix a "serious mistake" they called the "Hummer tax loophole." More than 30 vehicles -- including the Hummer H2, Chevrolet Suburban, Ford Expedition, Lexus LX 470 and Dodge Durango -- qualify for the break.
Congress amended the tax break in 2004, reducing it from $100,000 to $25,000, and it only applies to small businesses, though not all small companies are eligible for the full break.
The Alliance of Automobile Manufacturers, which represents Detroit's automakers, Toyota Motor Corp. and others, said the tax break is necessary.
"These are vehicles that small business owners across the country depend on for their way of life," said spokesman Charles Territo. "This effort is an assault on the hardworking men and women who rely on these types of vehicles for a living."
Markey claims the tax break can be misused. "Forget about zero-percent financing, this kind of incentive unfairly skews the market away from the more efficient, cleaner cars and SUVs American businesses and families say they want," Markey said. "Our government is essentially choosing Hummers over hybrids."
http://www.detnews.com/apps/pbcs.dll/article?AID=/20070616/AUTO01/706160358&theme=Autos-Green-tech-hybrids