Anymore you cant do d**k without credit, and everything regarding money will effect your credit in some way, shape, or form.
IE: Not paying your cell phone bill will kill credit. Not paying up on a COD shipment will kill your credit, and so on.
Credit is GOOD for you if you ever plan to move out of mommy/daddies house and live on your own.
Also, it's not so much that you can afford it NOW, look long term. Currently it is NOT a good time to be pulling a loan for a used vehicle that isn't going to be worth half what you paid for it before you even have half of the loan amount paid off. Point in case, over a year ago I got a loan to buy my truck and I wasn't thinking long term at the time. Back then, i could afford paying double the monthly payment and still have plenty of money left over to go out on the weekends and so on. However, now with the economy the way it is, and work slowing down. I'm down to making the MINIMUM payment to the credit union and that's about all i can afford to do (amongst other bills). Fortunately enough I am not upside down on it, and if i absolutely had to sell it I could. This is unfortunately not currently the case with the American auto industry.