The credit application you fill out for a car loan can temporarily lower your credit score, usually by fewer than five points, according to the MyFICO website. After a year of paying your loan, this black mark will have disappeared, and your credit may improve if you have a history of on-time payments and have avoided taking on excess debt.

Timely Car Loan Payments

The most important factor in your credit score -- accounting for 35 percent of the total score -- is a history of timely payments. If you make payments on time every month, your credit score should go up. However, a single late payment can ding your credit, and if the loan is large, the timely payment history might not be enough to compensate for the increased debt load.

Car Loan Debt Load

Your overall debt load is the second most important factor in your credit score, contributing to 30 percent of the total. If you take out a massive car loan or if you already have significant other debts, your car loan could actually harm your credit. However, if you quickly pay down the loan by paying it off or by paying more than the monthly minimum payments, you could still see an improvement in your score.

Role of Other Factors

It's impossible to analyze the effect of any single credit item taken in isolation, because your credit score is the result of your entire credit history. Even if you make timely payments on a relatively small loan, taking out several other loans, missing payments on another loan or closing multiple credit accounts can cause your score to plummet. Consequently, it's wise to focus on ensuring each account remains up to date and in good standing.

Anticipating Score Changes

There's no single number of points that a car payment or loan adds or subtracts from your credit score. Instead, your total score is a result of all the items on your report. If you only have one loan, then the payments you make will more significantly affect your score than if you have several loans and a handful of credit cards.