In the mid-1980s, Congress tightened rules about how much money

can be written off on luxury automobiles used for business -- but excluded vehicles with a gross weight of 6,000 pounds or more, partly an attempt to help farmers afford tractors, large trucks and other heavy equipment.

But many SUVs, including the 6,400-pound H2, fall into that heavyweight category, and now a new class of small-business owners and the self-employed, such as construction company executives, doctors, real estate agents and lawyers, is qualifying for the deduction.