As I discussed yesterday, having a car or truck over 6000 lbs exempts it from luxury car rules. Here is a table of autos and trucks with Gross Vehicle Weight Ratings (GVWR):
http://www.alphaleasing.com/businessaspects/over6000gvwr.asp
So go ahead and buy that gas guzzler for your business- you will have tons of business deductions for gas, insurance and depreciation.