Originally Posted by GraphiteZ

It is actually 15%. I don't quite understand how the money factor work.

Here is how I got my number.
Total cost of the car: 31,151+1,967+699+298 = 34,115
Residual of the car after 39 months = 18,984
That means the total depreciation of the car is 15,131

The deal requires him to pay 496 x 39 = 19,344

That means total interest in this deal is 4,213
With an Excel spreadsheet, that is 15.46% APR

Did I do it correctly?