I would recommend you wait to get another car unless you can't live with out it. I would concentrate your money on your credit cards as those interest rates are usually higher then car loan interest rates. The rule of thumb for credit cards regarding credit scores is to keep your balance less than 1/3 of your limit. This will give you a positve rating on your credit report. If you are able to completely pay off your credit cards every month you will see good score increases as well. There are a lot of misconceptions about how to fix credit and what works.
Are you interested in buying a home someday or do you own one? I ask because your credit scores drive mortgage loans in this day and age and its more important than ever to make sure you pay all of your bills on time.
Hope this helps