Auto loans
Is that 72-month payment as good as it sounds?
Stretching a car loan lowers the payment and raises the price. It also keeps you underwater — owing more than the car is worth — for years. Put two terms side by side and decide with the whole number in view.
The vehicle
The loan
Compare these two terms
Option A
Option B
Amount financed
$38,270
Price + tax + fees − down payment − trade-in
Interest saved
$1,852
Money that stays with you
Time saved
1 yr
Debt-free 1 year sooner
Total cost at 60 months
$46,999
Instead of $48,852 at 72 months
Taking 60 months instead of 72 costs you $105 more a month — and saves $1,852 in interest while getting you out 1 yr sooner.
72 months
The lower payment
- Monthly payment
- $678.50
- Total interest
- $10,582
- Total paid
- $48,852
- Underwater until
- month 38
60 months
The cheaper loan
- Monthly payment
- $783.32
- Total interest
- $8,729
- Total paid
- $46,999
- Underwater until
- month 24
The rate is negotiable too
priced over 60 monthsMost people negotiate the price of the car and accept whatever rate the finance office quotes. On this loan, one percentage point is worth $1,097.
Rate difference
1.50 pts
What walking in unprepared costs in rate
Per month
$27.34
Extra, every single month
Over the loan
$1,640
Extra interest across 60 months
The longer loan wins on the monthly number and loses on every other one. That is the whole trick.
Any month where the owed line sits above the value line, selling or totaling the car means writing a check to close the loan. That gap is what gap insurance exists to cover — and what a shorter term shrinks for free.
Nearly 3 years upside down
At 72 months you would owe more than this vehicle is worth until roughly month 38. Trading it in before then rolls the shortfall into your next loan, which is how people end up financing two cars at once.Monthly difference
$104.83
What the 60-month payment costs you extra
Interest per month of term
$146.97
Average, over 72 months
Cost of the longer loan
$1,852
Extra interest for the lower payment
Where a dealership actually makes its money
Not on the car. Margin on the vehicle itself is thin and shrinking — you can look up what almost anything is worth in about ninety seconds, and dealers know it. The money is made in the finance office, on the paperwork you sign after you've already decided you want the car.
Here is the mechanism, and it is not a secret — it's described in the CFPB's own guidance to lenders. A dealership doesn't usually lend you the money; it sends your application to banks and credit unions, and one of them approves you at a rate called the buy rate. The dealer is then allowed to write your contract at a higher rate, and the lender pays the dealership the difference — the dealer reserve, sometimes called participation.
So when the finance manager says “I got you approved at 8.40%,” the honest version may be “a lender approved you at something lower, and this is what we're writing it at.” That spread is legal, it's common, and nothing requires anyone to tell you it exists. The contract shows only the rate you're paying.
The same logic explains “what monthly payment are you looking for?” With four numbers in play — price, trade-in, term and rate — any payment you name can be produced from a great many combinations, most of which are worse for you. Name a payment and you hand over the ability to check.
Walk in with a rate already in your pocket
- 1Get preapproved before you shop. A credit union, your own bank, or an online lender. That number is now your ceiling — the dealership has to beat it or match it, and either outcome is a win for you.
- 2Do all your rate shopping inside two weeks. Credit scoring models bundle auto-loan inquiries made close together into a single inquiry — 14 days on older FICO versions and 45 on newer ones, so 14 is the safe assumption. Inquiries less than 30 days old are ignored by the score entirely.
- 3Settle the out-the-door price first. One number, including fees and tax, before financing, before a trade-in, before any mention of a monthly payment. Then negotiate the trade separately, then the financing.
- 4Let them try to beat your rate. Say the number out loud and invite them to do better. They often can — and a dealership that earns your financing fairly is a fine outcome. What you've removed is their ability to guess how much room they have.
- 5Price the add-ons separately. Extended warranty, GAP coverage, paint protection, VIN etching. Rolled into the loan, they quietly earn interest at your loan rate for the whole term. GAP in particular is usually cheaper from your own auto insurer.
- 6Ask two questions before signing. Is there a prepayment penalty, and is the interest precomputed? If interest is precomputed, paying the loan off early saves you little or nothing — which would undo everything else on this page.
Cheaper money, and what it costs you
A car loan isn't the only way to pay for a car, and the alternatives are usually cheaper on rate. They are not automatically better.
Home equity (a HELOC or equity loan) often carries a lower rate than any auto loan, and the interest is sometimes deductible. But it converts an unsecured-ish car debt into a debt secured by your house: miss payments on a car loan and you lose the car, miss them on this and you risk the home. Terms also run far longer, so a lower rate over fifteen years can still cost more total interest than a higher rate over five. Run both through the calculator above before you assume the lower number wins.
Money already sitting in your mortgage. An escrow surplus refund after a reassessment, or the payment you free up when PMI drops off, is real cash you were already living without. Using it as a down payment shrinks the loan without borrowing against anything.
A 401(k) loan looks cheap because you pay the interest to yourself — but the money is out of the market while it's out, and at many employers leaving your job makes the balance due fast. It is rarely the right tool for a car.
The rule that survives all three: compare total cost over the term you'd actually take, not the rate. A rate is a headline; the total is the bill.
Schedule — 60 months
60 payments · $8,729 interest
What this calculator assumes
- Why compare terms instead of just showing one payment?
- Because the finance office compares terms for you, and only mentions the payment. Putting 60 and 72 months next to each other turns a $70-a-month difference into a $2,000 difference, which is the number that should decide it.
- How is the amount financed calculated?
- Price, plus sales tax on (price − trade-in), plus fees, minus your down payment and trade-in. Many states tax the trade-difference this way; a few tax the full price. Adjust the tax rate to match your state if you want it exact.
- What is the 'rate you're preapproved for' comparing against?
- In indirect auto lending, a bank or credit union approves your application at a 'buy rate', and the dealership is permitted to write your contract at a higher one — the lender then pays the dealer that spread, known as dealer reserve or participation. The CFPB describes this arrangement in its 2013 guidance to auto lenders. Nothing requires anyone to tell you the buy rate, and your contract shows only the rate you're paying. Entering your own preapproval prices the same loan both ways so the spread has a dollar figure attached.
- Where does the depreciation line come from?
- A simplified curve: a 10% drop the moment a new car is driven off the lot, then roughly 15% of remaining value per year. Real depreciation swings widely by make, model and mileage — treat this as the shape of the problem, not a valuation.
- What about 0% dealer financing?
- Enter 0% and it works, but check whether taking the rate means giving up a cash rebate. If the rebate is larger than the interest on an outside loan, the 'free' financing is the more expensive option.
- What isn't modeled?
- Extended warranties, gap insurance, negative equity rolled in from a previous loan, and precomputed-interest contracts (common in subprime auto lending) where paying early saves you nothing.