it depends on more than your credit score. your score determines what interest rate you will get so you can possibly get the car but might have to pay a high interest rate, at least until your score is a little better, then you can refinance for a better rate. dealers will also look at current debt. they have an idicator called the debt to income ratio. its the percentage of your income that is debt on your credit report. if you have a copy of your credit report, you have an advantage cause you can see exactly what the dealer will be looking at. so if you eark 2000/mo and have current debt of 700/mo, your DTI (debt to income ratio) is 35%. the better this number, the more likely a dealer will lend to you. also, the higher your credit score (lets call yours 651 as an average of the 3), the higher DTI % you can generally have for the dealer to lend to you. If your credit score doesnt meet their guidelines, you will probably have to provide proof of income so as long as you really make what you disclose to them, you should be ok. since you're a first time buyer and probably have limited credit, they will probably want a cosigner since this will be a big loan for you early on in your credit history.
so to summarize, dealers look for more than just credit score.
also, just a tip, dont let them ask you what you want your payment to be. this is their way of stretching you out as much as possible and making as much money as possible off you. you need to focus on the purchase price of the car. make sure it's a reasonable price for the car. also, if you're doing a trade, dont mention the trade until the last second when you get the purchase price agreed upon. they use monthly payment and trade value to work people over big time. focus on purchase price and interest rate.