"what is the suv tax deduction?"

The SUV tax deduction only applies to certain especially big SUVs, ones over 6,000 pounds.  The intention is to allow people to deduct farm machinery and other work equipment, concentrating on the "utility" part of the "sport utility vehicle".  It includes Hummers and Land Rovers, but not the smaller family-sized SUVs.

You do have to declare it a business expense and insist that you’re driving it more than 50% for business, but the IRS has been pretty lenient on that.  Section 179 of the tax code lets you deduct it all in the first year rather than over the 5 years ordinarily required.  You can declare only $25,000 of it, plus 25% of the sticker price (the "bonus deduction"), which means you’re getting a pretty good break on the price of a great big vehicle.