The mortgage version of this question has a clean answer: compare your rate to a realistic expected investment return, and the side with the better number usually wins. The full mortgage math is here. The car loan version looks similar at first glance, and the underlying comparison (a guaranteed rate versus an uncertain one) is the same. But car loans come with a wider spread of interest rates, a much shorter runway, and an asset that's losing value the entire time, which changes which side of the comparison tends to win.
The rate spread is the first thing that's different
Mortgage rates cluster in a narrow band. Car loan rates don't. According to Experian's State of the Automotive Finance Market report for the second quarter of 2026, the average new-car loan rate was 6.35% and the average used-car loan rate was 11.19%, and that's just the average across all credit tiers. Experian's data for the first quarter of 2026 shows the actual range by credit score is far wider: superprime borrowers (a 781 to 850 score) averaged 4.55% on new cars, while deep subprime borrowers (a 300 to 500 score) averaged over 16% on new cars and over 21% on used cars.
That spread matters because the mortgage comparison assumes everyone's rate sits somewhere near a single market average. A car loan at 4.5% and a car loan at 18% are not the same decision wearing different numbers. One is a case for investing instead. The other isn't close.
The guaranteed-return framing, applied to a car loan
The same logic from the mortgage comparison applies directly: paying extra toward a loan earns you a guaranteed, risk-free return equal to that loan's interest rate, because every dollar of principal you eliminate early is a dollar that stops accruing interest at that rate. Investing the same dollar instead earns an uncertain, historically higher average return, with real volatility.
Using a 7% long-run average assumption for a diversified stock portfolio (a historical average, not a promise, and worth stress-testing against a worse decade before committing to it), a car loan above roughly 7% starts to favor paying it off early on pure expected-value grounds, the same way a mortgage above that threshold does. A car loan below that, especially a promotional 0% to 3% rate many manufacturers offer on new vehicles for qualified buyers, favors investing instead, assuming the monthly payment fits comfortably in the budget either way.
Why the short term changes the outcome more than the rate does
Here's where the car loan comparison genuinely diverges from the mortgage one, even at similar rates. A mortgage runs 15 to 30 years. A car loan typically runs 4 to 7 years. That shorter horizon cuts both ways, and it cuts harder than most people expect.
Less time for the guaranteed side to matter. Extra payments on a 6-year loan at 7% retire the loan maybe a year or two sooner than scheduled. The absolute dollars saved in interest are real but modest, because there isn't much time left for interest to compound against a shrinking balance in the first place.
Less time for the uncertain side to smooth out. A bad 2-year stretch in the market, the kind that averages out over a 20-year mortgage horizon, doesn't average out over a 5-year car loan term. If you're investing the difference with the specific goal of coming out ahead within the loan's own term, a short horizon means a market downturn in years 3 and 4 can leave you behind the guaranteed alternative with no time left to recover before you'd have been comparing the 2 outcomes anyway.
A worked example. Marcus takes a 5-year, $32,000 used-car loan at 9% (close to the current used-car average), with a monthly payment of roughly $665. He has $150 a month in spare cash and is deciding whether to apply it to extra principal or invest it.
Extra principal path: An extra $150 a month cuts the 5-year term to roughly 3 years and 10 months and eliminates every dollar of interest that would have accrued at 9% during the final 14 months. Total interest saved: approximately $1,380.
Invest path: $150 a month invested for 5 years at a 7% average annual return grows to roughly $10,700, of which about $1,700 is growth on top of the $9,000 contributed. On the average case, investing comes out ahead by a modest margin. But the entire outcome hinges on that 5-year window specifically; a materially worse 5 years in the market (which single 5-year windows absolutely can produce) flips the comparison, with much less time to recover than a 25-year mortgage comparison would have.
When paying off the car loan is the clearer call, regardless of rate
The loan rate is above 8% to 9%. At that point the guaranteed return is competitive enough with historical market averages, over a horizon too short to reliably outrun it, that the math stops clearly favoring investing.
The car is depreciating faster than the loan is amortizing. New cars lose a significant share of their value in the first year, with roughly 20% being a commonly cited rule-of-thumb range in industry depreciation data, and continue depreciating for several years after. If the loan balance is underwater relative to the car's resale value for an extended stretch, paying it down faster reduces that exposure, independent of the pure interest rate math.
You're carrying the loan into a job change, relocation, or other instability. A car loan with negative equity complicates selling or trading in the vehicle. If you're not confident in your income stability over the loan term, the guaranteed path has value the spreadsheet doesn't capture.
When investing the difference is the clearer call
You have a 0% to 3% promotional rate. These deals are common on new vehicles for well-qualified buyers, and at that rate, investing the difference wins on expected value by a wide enough margin that the shorter time horizon doesn't change the conclusion. Check the fine print first. Some promotional offers are deferred-interest structures where missing the payoff deadline applies interest retroactively to the full original balance, and some trade the low rate for giving up a cash rebate you'd otherwise get by financing conventionally or paying cash.
You have no other high-interest debt and a full emergency fund. The car loan math only makes sense to run once credit card balances and other higher-rate debt are handled first, and once you have cash reserves that don't depend on the car loan payoff for a safety margin.
The honest middle case
Most car loans fall in the 6% to 10% range, which is close enough to a reasonable long-run investment return assumption that the decision comes down less to pure math and more to how much the shorter time horizon's added risk bothers you. If a multi-year guarantee of eliminating a specific monthly payment sooner matters more to your peace of mind than the modest expected edge of investing instead, paying it down is a defensible choice, not an irrational one.
Frequently asked questions
What car loan interest rate makes paying it off early the clear winner?
Above roughly 8% to 9%, the guaranteed return from extra payments becomes competitive with a reasonable long-run market return assumption, over a loan term too short to reliably ride out a bad stretch in the market. Below that, especially at promotional rates under 4%, the math tends to favor investing the difference instead.
Does it matter if the car loan has a 0% promotional rate?
Yes, and it shifts the comparison heavily toward investing. A 0% loan has no interest cost to offset by paying early, so every dollar directed to extra principal earns a 0% return, while that same dollar invested earns whatever the market returns. Confirm the offer isn't a deferred-interest structure before relying on this.
How is the car loan decision different from the mortgage decision?
The underlying framework (guaranteed rate versus expected return) is the same, but 2 factors shift the car loan version: car loan rates span a much wider range by credit tier than mortgage rates do, and car loan terms are 4 to 7 years instead of 15 to 30, which gives market volatility far less time to average out before the comparison concludes.
Should I use a 0% loan even if I could pay cash?
Often yes, if the rate is genuinely 0% with no deferred-interest trap and investing the cash instead is feasible for you. Paying cash for a 0% loan forgoes a return you could have earned by investing that cash instead, for no corresponding benefit. The main exceptions are if the 0% offer requires giving up a cash rebate large enough to outweigh the benefit, or if carrying the monthly payment doesn't fit comfortably in your budget.