Buy That Car. If you are planning on buying a new car, truck or motorcycle, you may qualify for a federal tax break if you purchase it before Dec. 31. The break allows eligible taxpayers to deduct state and local sales and excise taxes paid on up to $49,500 of the purchase price. But the amount of the tax break, which can be used whether you itemize deductions on your tax return or not, begins to phase out for individual taxpayers whose modified adjusted gross income is $125,000 to $135,000 and $250,000 to $260,000 for joint filers.