You will use the amount reported on Form 1098-C as the value of your donated car. Your method is the stated value by the charity. The link below has information that you will find useful.
This does not answer the question. TurboTax asks for the "Method Used to Determine Value." There is a pulldown menu and the user has to choose from the following:
No entry
Appraisal
Average share price
Catalog
Capitalization of income
Comparative sales
Consignment shop value
Present value
Replacement cost new
Reproduction cost less depreciation
Thrift shop value
The question is: which of these is the right answer when the gross proceeds from sale are provided by the donee's 1098-C?
"Comparative Sales" would be the correct "Method Used to Determine Value".
The Donee sold the vehicle, either at auction or by way of advertising for buyers. The proceeds from that sale would be comparable to the sales proceeds for like-kind property. "Comparative sales" is the most accurate description for how the value is determined.
"Comparative sales" doesn't seem quite accurate. Is that Intuit's "official" advice or your workaround? Shouldn't there be an actual stated value choice? The charity reported the value based on actual price received at auction.
Determining the value of donated property would be a simple matter if you could rely only on fixed formulas, rules, or methods. Usually it is not that simple. Using such formulas, etc., seldom results in an acceptable determination of FMV. There is no single formula that always applies when determining the value of property.
This is not to say that a valuation is only guesswork. You must consider all the facts and circumstances connected with the property, such as its desirability, use, and scarcity.
"Actual Price received at Auction" is a less accurate amount because it is based on market conditions.
@lychee