Auto loan total cost
Last updated: 2026-08-14
The price on the car is not the amount you borrow. Sales tax, documentation and title fees, and any negative equity carried over from your last vehicle all get added before the loan is written.
What actually gets financed
A $30,000 car, $3,000 down, a trade-in worth $6,000 that still has $8,000 owing on it, sales tax at 7% and $500 of fees:
| Line | Amount |
|---|---|
| Vehicle price | $30,000 |
| Sales tax and fees | +$2,600 |
| Down payment | −$3,000 |
| Trade-in credit | −$6,000 |
| Negative equity rolled in | +$8,000 |
| Amount financed | $31,600 |
You are borrowing more than the car costs, and $2,000 of that debt belongs to a vehicle you no longer own. Tax treatment of trade-ins varies by state — some tax only the difference after the trade credit, which changes the figure.
Negative equity is the expensive part
Rolling an old loan balance into a new one is how buyers end up permanently underwater. The old debt gets refinanced at the new rate over the new term, and the new car begins depreciating immediately on top of it.
Do it twice and the carried balance compounds. Each cycle the financed amount drifts further above what the vehicle is worth, which raises the payment, extends the term, and makes the next trade worse still.
Long terms and the underwater window
Seventy-two and eighty-four month auto loans exist because they make expensive cars look affordable monthly. The problem is that cars depreciate faster than long loans amortize.
On a long term you can spend years owing more than the car is worth, which matters the moment you need to sell, or the car is written off and the insurer pays market value rather than your balance. A larger down payment and a shorter term both shrink that window.
Judge the total, not the payment
Dealer negotiations often run on monthly payment, because almost any payment target can be met by extending the term. The figures worth holding are the out-the-door price, the amount financed, the rate, and the total of payments.
Arranging financing separately before you shop is usually cheaper, and it turns the conversation back to the price of the car.
Work out the real cost
The auto loan calculator takes vehicle price, down payment, trade-in value, any payoff still owed, tax and fees, and estimates the payment and total cost from the amount actually financed. The loan comparison calculator compares two financing offers.
Related reading: APR vs interest rate.
What the term does to a car loan
Long auto terms lower the payment and extend the period during which the balance exceeds the car’s value. That gap is where the risk lives.
| Term | Monthly payment | Total interest | Roughly when equity turns positive |
|---|---|---|---|
| 36 months | $1,081 | $3,910 | Around month 8 |
| 48 months | $838 | $5,236 | Around month 14 |
| 60 months | $693 | $6,591 | Around month 22 |
| 72 months | $597 | $7,975 | Around month 32 |
On a seventy-two month loan you spend more than two and a half years owing more than the car is worth. If it is written off in that window, insurance pays the value and you still owe the difference.
Common questions
Why is the amount financed higher than the price?
Sales tax, title, registration and dealer fees are usually rolled in, and negative equity from a trade-in is added on top. The financed figure regularly exceeds the sticker price.
What is negative equity?
Owing more on your current car than it is worth. Rolling it into the next loan means financing debt on a vehicle you no longer own, and doing it twice is how buyers end up permanently underwater.
Is a longer auto loan a bad idea?
Long terms lower the payment but the car depreciates faster than the balance falls, so you spend years underwater. That matters if the car is written off or you need to sell.
Should I take dealer financing or arrange my own?
Get a pre-approval first so you have a rate to beat. Dealer financing is sometimes genuinely cheaper through manufacturer subsidies, and a pre-approval is how you find out.
Related reading
The rest of this series, and the calculators that let you run the idea on your own numbers.
More loan guides
Try it with your figures
See also all guides, every calculator, and the calculation methodology behind these estimates.