The IRS does have some special rules for donating cars. Instructions for Form 8283 Noncash Charitable Contributions say the following about donating cars:
"If you donate a qualified vehicle with a claimed value of more than $500, you cannot claim a deduction unless you attach to your return a copy of the contemporaneous written acknowledgment you received from the donee organization. The donee organization may use Copy B of Form 1098-C as the acknowledgment. An acknowledgment is considered contemporaneous if the donee organization furnishes it to you no later than 30 days after the:
- Date of the sale, if the vehicle was sold [by the donee organization] in an arm's length transaction to an unrelated party, or
- Date of the contribution, if the vehicle will not be sold by the donee organization before completion of a material improvement or significant intervening use, or the vehicle will be given or sold to a needy individual for a price significantly below FMV in direct furtherance of the organization's charitable purpose of relieving the poor and distressed or underprivileged who are in need of a means of transportation."