First off, your calculations are wrong. If you borrow $4,000 for 4 years at 9.5% you will not be paying about $400 extra. You will be paying more than twice that much. Your monthly payment will be about $100.50. Take that times 48 an you'll see that you're paying more than $800 in interest.
Here's a forumla that you can plug into a spreadsheet to calculate your monthly payments on a loan (it may be off by a couple of cents from what the bank will tell you, but it will be very close):
=((((C3*(C5))/12)/(1-(1/((1+((C5)/12))^(C4*12)))))*100+0.5)/100
C3=original loan amount
C4=term of the loan (length of the loan in years)
C5=interest rate (0.095 would be 9.5%)
The following is going to be long, but it'll pay you greatly in the long run to read it. I made all of the usual mistakes when I was young. I learned from my mistakes. I hope others can learn from my mistakes as well, instead of just making the same ones over.
RULE NO. 1: Pay yourself first! If you are not putting anything at all into savings, the very first thing you MUST do is start! Even if it's only $10 a month, at least that's a beginning. There is always a way to squeeze a few dollars a month for savings, if you really want to. It doesn't matter how much you earn, you will NEVER be rich if you can't live within your means. It doesn't matter how little you earn, you WILL be rich if you CAN live within your means!
The best and easiest way to pay yourself first is if the company you work for has a 401k program--GET INTO IT!!! If they will match some of your contribution then you are STUPID if you don't contribute enough to get as much as they are willing to match!
RULE NO. 2: Pay off credit cards each and every month! Credit card debt is the main reason that most Americans can't get ahead. They go out and buy stuff they can't afford just because they can charge it and only pay a little each month (more on this in rule no. 4). What they don't realize is that each month's payment is MOSTLY interest and hardly any of it goes to paying off the debt. This is the fastest, easiest, and STUPIDEST way to get into debt that there is!
RULE NO. 3: Use credit cards wisely. Rule no. 2 does not mean that you shouldn't have or use credit cards. The way to build up a good credit record is to use credit wisely. Get credit cards, but pay them off in full each month. Borrow money, but be sure you can afford the payments, and be sure that you're borrowing it for purchases that are worth what you're paying. Build up good credit and you'll have doors opened to you in the future; the most important one being that, with a good credit rating, when you're ready to buy a house, banks will be falling all over themselves to give you the very best rates and the lowest closing costs out there.
RULE NO. 4: Never purchase ANYTHING based on the monthly payment. The sales people can make the monthly payment anything you want it to be, just by extending the length of the loan. I can sell you that Ducati for $50/month, and bleed you dry at a 15% interest rate. All I have to do is make it a 20 year loan! The sales people WILL take advantage of you if you let them talk to you in terms of monthly payment. Negotiate a purchase price FIRST, and only then talk about financing.
RULE NO. 5: Never, EVER allow yourself to be "upside down" on any depreciating asset. "Upside down" means that you owe more on it than it is worth. This is not a very good idea on a house, which usually goes up in value. It is an EXTREMELY bad idea on anything like a car, boat, motorcycle, or anything else that steadily goes down in value. In order to stay "rightside up" on car, bike, etc. loans you have to make a substantial down payment (20% at least, 30% is better) and you have to keep the term of the loan relatively short (4 years at the MOST! 3 years is better).
Good luck!
. My score was a 4 because I put my foot down in the uturn (damn dirtbike habit 
