Charitable Automobile Red-Tape Simplification Act of 2015 or the CARS Act of 2015 

This bill amends the Internal Revenue Code, with respect to the tax deduction for charitable contributions, to modify the substantiation rules for donations of qualified vehicles (i.e., motor vehicles manufactured primarily for use on public streets, roads, and highways and boats or airplanes) with a claimed value exceeding $500 but not $2,500, to require: (1) a statement with respect to such qualified vehicles and a good faith estimate of their value at the time of donation; and (2) a contemporaneous written acknowledgement of the contribution by the donee organization, with information about the donor and the qualified vehicle.