APR = annual percentage rate
You aren't paying 8% total interest, you are paying 8% interest a year on the principle remaining. Thus, that interest compounds and you will pay $3780 in interest if you pay on time but are never ahead on your payments. Each month you will pay down a higher amount of principle and pay less in interest, but you will be paying a lot in interest the first year + of your loan.
Check out the bankrate link above, fill in the info and click on Show/Recalculate Amortization Table. That will show you what you will pay towards principle and what you pay in interest every month and for the life of the loan.