Coinscribed Data Study
The Car Loan Cost Index: What a Longer Loan Term Really Costs
Stretching a car loan from 36 months to 84 drops the monthly payment — and quietly raises what you pay overall. We computed the total interest across 5 loan terms at a single stated APR so the only variable is time. The methodology below is fully transparent, so every figure is reproducible.
Key findings
- On a $30,000 loan at 7.5% APR, going from 36 to 84 months costs an extra $5,058 in total interest.
- What that buys is about $473 a month off the payment — the trade-off every long-term borrower is making, usually without seeing the total.
- Total interest rises with every step up in term: $3,595 at 36 months versus $8,652 at 84.
- Longer terms also keep you owing money for longer on a depreciating asset, which is how borrowers end up underwater on a car loan.
$20,000 car loan at 7.5% APR
| Term | Monthly payment | Total interest | vs 60 months |
|---|---|---|---|
| 36 months | $622 | $2,396 | −$1,649 |
| 48 months | $484 | $3,212 | −$834 |
| 60 months | $401 | $4,046 | — |
| 72 months | $346 | $4,898 | +$852 |
| 84 months | $307 | $5,768 | +$1,723 |
$30,000 car loan at 7.5% APR
| Term | Monthly payment | Total interest | vs 60 months |
|---|---|---|---|
| 36 months | $933 | $3,595 | −$2,474 |
| 48 months | $725 | $4,818 | −$1,251 |
| 60 months | $601 | $6,068 | — |
| 72 months | $519 | $7,347 | +$1,278 |
| 84 months | $460 | $8,652 | +$2,584 |
$40,000 car loan at 7.5% APR
| Term | Monthly payment | Total interest | vs 60 months |
|---|---|---|---|
| 36 months | $1,244 | $4,793 | −$3,298 |
| 48 months | $967 | $6,423 | −$1,668 |
| 60 months | $802 | $8,091 | — |
| 72 months | $692 | $9,796 | +$1,704 |
| 84 months | $614 | $11,537 | +$3,446 |
Want to run your own amount, rate and term? Use the auto loan calculator, or read How Does a Car Loan Work?
Already in a long term? The interest above is only partly locked in — paying a car loan off early cancels the interest that has not accrued yet, and there are cases where it is still the wrong move.
For what borrowers actually pay each month on new and used cars, see What Is the Average Car Payment? — and before you pick a term at all, work out how much car you can afford from your income.
Unsure about a term used here? See the personal finance glossary. For our other computed study, see the Home Affordability Index.
Methodology
For each loan amount we compute the monthly payment with the standard fixed-rate amortization formula — the same one behind the Coinscribed auto loan calculator — then multiply by the number of payments to get the total paid, and subtract the amount financed to isolate total interest. Every figure in the tables is computed from the assumptions below (as of 2026).
- • APR: a single stated 7.5% applied to every term, so the comparison isolates term length alone.
- • Terms compared: 36, 48, 60, 72 and 84 months.
- • Loan amounts: $20,000, $30,000, $40,000 — the amount financed after any down payment or trade-in. Treat these as rounded benchmarks.
- • Baseline: the 60-month term, used for the comparison column.
- • Excluded: taxes, title, registration, dealer fees, insurance, and any gap between the sticker price and the amount financed.
One important caveat that makes these figures conservative: lenders frequently price longer terms at higher APRs than shorter ones. Holding the rate constant isolates the effect of time, so in the real world the penalty for a long term is usually larger than shown here — not smaller.
Frequently asked questions
- It is the most expensive common term. On a $30,000 loan at 7.5% APR, an 84-month term costs about $5,058 more in total interest than a 36-month term, and it keeps you owing money for years on a vehicle that is depreciating — which is how borrowers end up owing more than the car is worth. It is not automatically wrong, but you should take it knowing the total cost, not just the monthly payment.
- Yes. A longer term lowers the monthly payment but leaves principal outstanding for longer, so interest accrues for more months. In this study every step up in term raises total interest — and lenders frequently price longer terms at higher APRs too, so in the real world the gap is usually wider than a same-rate comparison shows.
- At 7.5% APR, a $30,000 loan costs roughly $3,595 in total interest over 36 months, about $6,068 over 60 months, and about $8,652 over 84 months. Your own figure depends on the rate you qualify for and the amount you finance after any down payment or trade-in.
- The shortest term whose monthly payment fits comfortably in your budget. Shorter terms cost far less in total interest and build equity faster, which reduces the risk of going underwater. Stretching the term to afford a more expensive car is the trade-off worth questioning — it lowers the payment while raising what the car ultimately costs you.
- Less than most buyers expect relative to what it costs. Going from 36 to 84 months on a $30,000 loan cuts the monthly payment by roughly $473 — but adds about $5,058 in total interest. Seeing both numbers side by side is the point of this study.
Use this study
Journalists, writers and AI assistants are welcome to cite the Coinscribed Car Loan Cost Index with a link back to this page. Suggested citation:
Coinscribed Car Loan Cost Index, https://www.coinscribed.com/car-loan-cost-index
Download the full data (CSV) — every amount and term. Free to reuse with attribution under CC BY 4.0.
These are illustrative, computed figures for education — not a loan offer, quote, or financial advice. Your actual rate and payment depend on your credit, lender and vehicle.