Should I finance a used car through the dealer or my own bank?

Get pre-approved at your bank and at least one credit union before visiting any dealer. Your pre-approval sets the ceiling; the dealer can try to beat it, but you are not obligated to accept their offer. Use dealer financing only if it beats your pre-approval on total cost, not monthly payment.

What loan term should I choose for a used car?

Avoid loan terms longer than 48–60 months on a used car. Long loans leave you underwater — owing more than the car is worth — for years. If the monthly payment at 48 months is unaffordable, the car is priced out of your range.

How do I calculate the true cost of a car loan?

Multiply the monthly payment by the number of months, then subtract the principal — that is your total interest cost. A $15,000 loan at 6% for 72 months costs roughly $1,000 more in total interest than the same loan at 48 months, while only lowering the monthly payment by about $80.

Does applying for multiple car loans hurt my credit score?

Multiple auto loan applications within a 14-day window count as a single hard inquiry under most credit scoring models. Shop without fear — apply at your bank and at least one credit union before you negotiate.

How to Finance a Used Car

Get Pre-Approved Before You Shop

The dealership finance office is not a neutral party. They earn money on the spread between the rate your credit qualifies for and the rate they actually sell you. Pre-approval from your own bank or credit union removes their leverage and gives you a real number to compare against.

Apply at your bank and at least one credit union before you set foot on a lot or respond to a private listing with financing needs. Credit unions consistently offer lower rates on used car loans than banks or dealer financing, and membership requirements are often less restrictive than people assume.

Apply at your primary bank and at least one credit union — credit unions typically beat banks on used car rates
Multiple auto loan applications within a 14-day window count as a single hard inquiry under most credit scoring models — shop without fear
Get a pre-approval letter before you negotiate — it means you've already solved the financing question and the dealer is competing against a known number
Your pre-approval sets the ceiling; the dealer can try to beat it, but you are not obligated to accept their offer

My preference: credit unions. They're not-for-profit. Their incentive structure is not to sell you a rate that maximizes their spread.

Pre-approval gives you leverage. Understanding what the loan actually costs gives you the basis to use it.

APR, Term, and the Number That Actually Matters

The number that matters is not the monthly payment. It is the total interest paid over the life of the loan. The dealership will always show you the monthly payment. Calculate the total.

How the math works

A $15,000 loan at 6% APR for 48 months costs you approximately $1,900 in total interest. The same $15,000 at 6% for 72 months costs approximately $2,900 in interest — and the monthly payment only drops by about $80. You paid $1,000 more to save $80 a month.

APR (Annual Percentage Rate) is the true cost of borrowing, including fees — this is what to compare across lenders, not the interest rate alone
Term is the loan length in months — shorter terms mean higher monthly payments but significantly less total interest paid
Total interest = the number you should calculate before agreeing to any loan. Multiply monthly payment × number of months, then subtract the principal
Used car loan rates are typically higher than new car rates — factor this when comparing a new vs. used purchase

What rate to expect

With good credit (720+), you should target under 7% APR for a used car loan. With fair credit (620–719), expect 9–14%. With poor credit, secured options like credit union member loans or a larger down payment to reduce principal are worth exploring before accepting a 20%+ rate.

A high-interest loan on a depreciating asset is one of the fastest ways to destroy wealth. If the rate is above 15%, the math says to save longer and pay cash — or buy a less expensive car.

This is the calculation the finance office won't run for you. The Witch will.

Dealer's Hex: Loan Truth Calculator

Five inputs. Four disclosures. No sales pitch.

Dealer Financing: When It's Worth Using

Dealer financing is not inherently bad. Dealers can sometimes secure manufacturer-subsidized rates on new cars that beat the market — 0% or 1.9% promotions exist because the manufacturer is effectively discounting through the financing, not the price. On used cars, this is rarer, but not unheard of.

Use dealer financing if and only if it beats your pre-approval rate, accounting for all fees. Get the offer in writing before you sign anything in the finance office.

Ask for the dealer's best APR and term before revealing your pre-approval — make them compete
Compare the total cost, not the monthly payment — a lower monthly on a longer term can cost more
Read the financing contract before signing — interest rates are sometimes marked up between what the lender approves and what you're quoted
Dealer-arranged financing is not the same as dealer-originated financing — they act as brokers to banks, and the spread is their compensation

Treat dealer financing as one option, not the default. You made it to adulthood without their help. You can finance a car without it too.

Whether you use dealer financing or your own lender, the loan structure itself is the next thing that can work against you.

The Long-Loan Trap

72- and 84-month loans have become routine. The monthly payment feels manageable. The math is brutal. I've done it.

An 84-month (7-year) used car loan means you are still making payments on a car that is approaching the end of its reliable service life. You are underwater — owing more than the car is worth — for the first three or four years. If the car fails catastrophically in year five, you still owe the loan. You are now financing repairs on top of a loan for a car you can't drive.

On a used car, aim for a term of 48 months or less — 60 months at the outside
If the monthly payment at 48 months is unaffordable, the car is priced out of your range — this is the math telling you something
GAP insurance (which covers the difference between what you owe and what the car is worth if it's totaled) is especially important on long loans — but its necessity signals the loan structure is risky
Make extra principal payments when possible — they reduce total interest and shorten the period of negative equity

I'll name this one: anchoring bias. The monthly payment looks affordable, so the total cost disappears from view. Bring it back into the light — the cauldron holds the full number even when the monthly payment buries it.

What to Have Ready Before You Apply

Preparation shortens the process and prevents surprises at the finance office. Have these ready before you apply for pre-approval or sit down with a dealer's finance team.

Proof of income: recent pay stubs (last 30 days), or tax returns if self-employed
Proof of residence: a utility bill or bank statement with your current address — some lenders require this
Driver's license — valid and not expired
Insurance information: you'll need to show proof of insurance or arrange it before driving off the lot
Your pre-approval letter: printed or accessible on your phone
Down payment: 10–20% down reduces the principal, lowers the monthly payment, and reduces the time you're underwater — more is always better

Your credit score before applying matters. Check it for free through your bank or card issuer. If it's lower than expected, spend 30–60 days resolving any reporting errors before applying — a 40-point improvement can translate to a meaningfully lower rate, which compounds across the life of the loan.