If your Jeep is in good shape then keep driving it until you can't anymore or you get your credit up. Trust me, you do not want to have a car payment with bad credit because your payment will be expensive! I absolutely had to buy a new (well, new to me) car with bad credit. It's a 1999 and I'm paying over $300 a month. Just wait and build up your credit first while saving up some money. My husband used to sell cars and they usually like to see about 10-20% down.