What is GAP insurance for a car, and what is a simple interest auto loan?

GAP (Guaranteed Asset Protection) insurance covers the difference between what you owe on an auto loan and what your car insurer pays if the vehicle is totaled or stolen. A simple interest auto loan calculates interest on the outstanding balance, so extra payments reduce the interest you owe.

GAP insurance: what it covers and when it matters

New vehicles depreciate quickly. If your car is totaled shortly after purchase, your standard auto insurance pays the vehicle's current market value, which can be significantly less than the loan balance you still owe. GAP insurance is designed to cover that shortfall. The CFPB notes that standard auto insurance only pays up to the value of your vehicle — GAP covers the loss if your loan balance is higher than that value.

Most useful when: you made a small (or no) down payment, chose a long loan term, or are financing a rapidly depreciating vehicle.
Less useful when: you put down 20%+ with a short loan term — you're unlikely to be underwater.
It's optional. You generally cannot be required to purchase GAP to obtain an auto loan, and you have the right to cancel it.
Shop the price. GAP can be purchased from your auto insurer, a bank, or a credit union — often cheaper than dealer-financed GAP rolled into your loan.

Simple interest auto loans: how they work

Most U.S. auto loans use simple interest. The CFPB explains that simple interest is calculated based on your actual outstanding balance — so extra payments reduce principal directly and cut the interest that accrues going forward.

Simple interest vs. precomputed interest

The alternative — precomputed interest — adds all interest to the principal upfront and splits it into fixed installments; with precomputed loans, additional payments don't reduce the interest owed the way they do on a simple interest loan. Precomputed loans are uncommon; if you plan to pay off early, confirm the structure before signing.

Data points

You have the right to cancel optional add-on products like GAP at any time; if GAP is rolled into the loan, its cost increases the total interest you pay. — CFPB — Guaranteed Asset Protection (GAP) insurance
Simple interest calculates interest on the actual outstanding balance, making early or extra payments effective at reducing total interest. — CFPB
Standard auto insurance pays only up to the vehicle's current value, which is why a loan balance above that value creates a 'gap.' — CFPB

Key takeaways

GAP insurance is most valuable when your loan balance could exceed the car's value — typical with low down payments or long terms.
GAP is optional; compare prices from your insurer vs. the dealer before buying.
Most auto loans use simple interest — extra payments cut principal and reduce total interest owed.
If you plan to pay off early, confirm the loan is simple interest (not precomputed) before signing.