How long will it take to improve my credit score?

If the car dealer belongs to the credit bureau, that's a start. I believe most student loans also belong to the credit bureau. So the first step is run your free credit reports. For online, go to annualcreditreport.com. By mail, call Trans Union Toll free @ 1-877-322-8228 for all 3 free reports. I believe the fee is $20 for all 3 credit score. A FAIR is 620/659, GOOD 660/749 and EXCELLENT 750/840. It usually goes up between 5 to 10% per month providing you are paying on time.