[SteveB05]

You need to talk to a financial advisor to really learn simple interest loans...you can really get screwed if you don't know what you are looking at.

Interest is part of the loan, and that is where they (dealer or bank) make their money (if you let the dealer finance the deal, they also make money on the buy rate, but that's another conversation). Most of the time, you'll want to pay dealer fees (finance, not prep), taxes and registration outside of the loan if you have enough to do that and pay the down payment.

Now for the amount, your lender will have a cap on how much you can borrow for a certain car. You really don't want to be close to that as the more you owe now, the more you will owe when it comes time to get rid of it. Try not to ever be upside down (wishful thinking for most of us) which means you owe more than the car is worth.