To help your credit you could take a loan against cash. Example:
1.) Take a two thousand dollar loan.
2.) Open a new Share (it's a virtual container for cash) with your Credit Union/Bank
3.) Figure out the total Interest for that loan and put that amount in the Share too.
4.) Forget about the loan.
Buying a house Bianary0x01 said will put the credit through the roof too. However, making payments on your car will also raise your score quite high too.
Personally I would pay a large amount on the car and take a reasonable loan. Figure out how big you want your monthly payment to be and put down a large enough down payment to get you that number.
Try this:
Auto loan calculator - Bankrate.com