With the cost to own a new vehicle rising, it's more important than ever to consider what you'll pay for a car loan and to shop for the best interest rate.

The average new car loan interest rate reached 5.5% in 2018, up about 1 percentage point from the previous year, according to Ben Bartosch, J.D. Power's manager of forecast analytics. Meanwhile, a new car purchase price is $33,000, on average, he says. That means a buyer will pay thousands of dollars in interest on a 60-month loan.

With the shift in the loan market, anyone looking to buy a car or refinance a loan needs smart strategies. Here are five things financial and automotive experts say will help you lock in financing that fits your budget.

1. Check your credit. If you don't know your credit score, you don't know what interest rate you could qualify for. Additionally, if you find a problem on your credit report, you can fix it before entering the car-buying process. And, if you already have a loan, you may be able to refinance into a lower rate.

Your credit score is available for free from many personal finance websites, banks and credit card issuers. And you can use AnnualCredit­Report.com to request the free credit reports you're entitled to every 12 months from the three major credit bureaus.

2. Shop around for the best rate. The loan-shopping process should start long before the car-buying process, Bartosch says. Calling around, or submitting online applications, could save you hundreds of dollars.

"Most people just think of going to the dealer to get a loan," says Sonia Steinway, president of auto loan company Outside Financial. But "there's a whole world of options available to them." She says credit unions offer some of the lowest rates and the best customer service.

In comparing loan offers, keep the loan amount, down payment and loan terms the same.

3. Design a loan you can afford. Once you know the interest rate you qualify for, use a car loan calculator to estimate your monthly payment. Aim to spend no more than 10% of your take-home pay on your loan payment and less than 20% for total car expenses, which includes gas, insurance, repairs and maintenance.

4. Get preapproved for a car loan. Preapproval can help you get the most competitive rate. Michael Bradley, internet sales manager at Selman Chevrolet in Orange, Calif., encourages buyers to apply for financing before they get to the dealership, then to ask the dealer to beat their rate.

Recently, Bradley has seen more shoppers coming in with preapproved loans from credit unions, but others, he says, are waiting for 0% financing from car manufacturers' lending companies. These loans aren't offered as frequently as in the past, he says.

5. Carefully review the contract. While the loan contract is long and the verbiage is dense, it's important to review it carefully before signing. Double-check the numbers using a loan calculator. Mistakes — sometimes intentional — do happen.

If the numbers don't add up, make sure the lender hasn't slipped in extra items you don't want, like an extended warranty or gap insurance. And question any extra fees you weren't told about initially or that other lenders don't charge.

Philip Reed is a writer at NerdWallet. E-mail: preed@nerdwallet.com Twitter: @AutoReed