I called to receive the interest paid on my car. but they could only provide me the percentage of 4.74. how do i convert that into a dollar amount?

Exactly where are you trying to enter this? If you are taking auto expenses for your business, just enter the amount paid for the vehicle and you will depreciate it using actual expenses. If this is for sales tax, you should have a sales receipt with the amount of sales tax listed.

This isn't exactly the correct math, since it would already be incorporating the sales tax in the total, but $20,000 x 4.74%=$948.

even that computaion is not correct since ebry month you pay principal that redues the interest charge because there is less debt outstanding

who did you call the seller or the finance company? it should be the latter.