New car vs old car: compare total cost over the years you keep it
Quick answer
To compare a new car with an old one, add up each option's total cost over the same number of years and miles: loan payments, insurance, fuel, maintenance and repairs, minus expected resale. The older car usually costs less to own but more to repair. Enter both in the calculator to see your planning estimate.
New-car ads talk about features and a payment. Used-car ads talk about a lower price. Neither ad adds insurance, fuel, and the years you will keep the vehicle.
The fair question is: over the same miles and the same keep period, which pile of cash is smaller, and what do you still have at the end? That is a job for the all-in car cost calculator, not for a rule that “used is always cheaper” or “new is cheaper because of warranty.” The same calculator works whether the other option is the car already in your driveway, a used car, or a new one.
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How to run a new vs old car comparison in the calculator
The calculator estimates one car at a time. Run it once for each option, write down the results, and compare them. Read Net after resale first for the overall comparison, then Cash out for the money that actually leaves your account.
Use the same keep period and miles for both
Set Years you keep it and Miles per year to the same values in every run. If you will commute the same distance either way, both cars get the same miles. If the keep period or mileage changes between runs, the calculator is comparing different situations, not different cars.
Inputs for the car you have
The calculator needs a price above zero, so treat the car you already own as if you were “buying it back” at today's value:
- Price before tax: what the car is worth today — a trade-in or private-sale offer you actually have in hand, not a guess you hope for.
- Down payment: today's value minus any loan payoff left. If the car is paid off, set the down payment equal to the price so there is no loan.
- APR % and Term (months): if you still owe money, your current loan's APR and the months left. If it is paid off, these do not change the result (there is no loan balance).
- Insurance $ / month: your current premium.
- MPG and Fuel $ / gallon (or kWh/100 miles and $/kWh for an EV): your logged MPG if you track it.
- Maintenance $ / year: routine service plus the repairs you expect over the keep period, spread per year. If a mechanic has quoted a repair, add it.
- Resale value %: what you expect the car to be worth at the end of the keep period, as a percent of today's value.
Why count today's value? Keeping the car means not selling it today. Putting that value in as the price and down payment makes the “keep” run carry the same money the “replace” run gets from a trade-in, so the two results line up.
Inputs for the new or used replacement
- Price before tax: the out-the-door price you have been quoted for that specific car, before tax.
- Down payment: the cash you will put down plus any trade-in equity from your current car (its value minus any payoff).
- APR % and Term (months): the rate and term you have been offered for that vehicle. New-car and used-car rates are often different; do not reuse one for the other.
- Insurance $ / month: a quote for that VIN or year/make/model, with the same drivers and ZIP code.
- MPG, Maintenance $ / year, Registration $ / year and Resale value %: for that car, at the end of the same keep period.
The calculator does not include sales tax, dealer fees or your actual insurance quote unless you enter them. Every figure it shows is a planning estimate, not a quote.
Keep your current car vs replace it
Keeping the car you have and replacing it are both costs, just in different lines. The calculator lets you see them side by side instead of comparing a repair bill with a monthly payment.
Repair bills vs a new payment
A paid-off older car can show a low monthly all-in number even with a high maintenance allowance, because the loan line is zero. A replacement adds a loan line and usually lowers the maintenance line. Neither is automatically cheaper. Put a written repair estimate into the old car's maintenance line, then try a higher number. If a bigger repair allowance flips the result, the decision depends on repairs, and that is worth knowing before you sign. This page does not tell you to keep or replace; it shows which inputs decide it.
Resale or trade-in value now vs later
Your current car is worth something today and probably less at the end of the keep period. A replacement starts at a higher price and also loses value. Use a resale percent on each side that you could defend, not a story. The depreciation and resale guide explains how to choose that number. If the replacement only “wins” with an optimistic resale percent, the result depends on the market, not on what you will actually pay.
A longer loan can make a replacement's payment look closer to “no payment,” but CFPB notes that “the longer the loan term, the lower your monthly payments but the more you'll pay in interest over the life of your loan.” See longer loan terms and total cost and same payment, different cost.
Used vs new: what usually differs, and what should not
Hold miles and years kept constant first. If you will commute the same distance, both cars get the same miles. Then let the car-specific lines move in the calculator: price, down payment, APR (used rates are often different from new), term, insurance, MPG, and maintenance.
Price is the obvious gap. A used car that is a few years old has already taken an early depreciation step that a new car has not. That does not mean the used car will hold the rest of its value. It means the new-car buyer is the one who will pay that first step if they sell soon. Model it with a resale percent on each side, not with a story. See depreciation and resale.
Maintenance is the used-car line people skip
A new car has a factory warranty for a defined period and mileage. That warranty is not infinite and does not cover tires, wear items, or everything that can break. A used car may have some warranty left, a third-party contract, or none. The honest move is to raise the used maintenance allowance if the vehicle is older, has high miles, or has a known service coming — timing belt, tires, brakes — and to keep a non-zero allowance on the new side for the services you will still pay for.
Do not invent a shop study. Use a written estimate when you have one, or a round number you would not be surprised to spend, and test a higher one. If a higher maintenance number flips the ranking, the decision is sensitive to repairs. That is useful information before you buy a cheap car that is expensive to keep.
Insurance, fuel, and the rate you are actually offered
A newer car can cost more to insure because repairs and replacement value are higher. A used performance car can cost more than a new mundane one. There is no shortcut: quote both VINs, or both year/make/model combinations, with the same drivers and ZIP code. Put those premiums in the calculator. The insurance and total cost guide explains why a reused premium from a different car is the wrong input.
Fuel economy is a vehicle trait, not a new-versus-used trait. A used hybrid can beat a new truck. Use the sticker or your logged MPG for each car. If the used car has a documented appetite for premium fuel, use that price.
APR is often different for new and used. Captive new-car offers and used-car bank rates are not interchangeable. Enter the rate you have been quoted for that vehicle. A cheaper used price with a much higher APR can give back some of the savings in interest. Check that on the ownership calculator before you call the used car a bargain.
A keep-period pattern
Pick three or five years — the time you believe, not the time a salesperson prefers. Run the new car with its price, its rate, a maintenance allowance that matches a warrantied early life plus tires, and a resale percent you would defend for a three- or five-year-old example of that model. Run the used car with its out-the-door price, its rate, a higher maintenance allowance if age warrants it, and a resale percent for a yet-older car at the end of the same keep period. Run the car you have now the same way, using the inputs above.
Read cash out first. That is the money that leaves. Then read net cost after resale. If the new car only “wins” on an optimistic residual, you are betting the market, not reading a receipt. If the used car only wins when maintenance stays implausibly low, you are betting the shop.
Compare all three in the calculator
Condition, history, and what the calculator cannot see
A used price is not a complete description. Title status, accident history, remaining factory warranty, and a pre-purchase inspection sit outside the form. If an inspection finds work, add the estimate. If you skip the inspection, the maintenance line is a guess you chose to make. The calculator will not warn you. It will only add the number you typed.
You can check title and salvage history through the Justice Department's National Motor Vehicle Title Information System.
Certified pre-owned programs add a price and some coverage. Enter the CPO price. If the extra coverage lowers what you expect to spend at the shop, lower maintenance — by an amount you can explain, not by zeroing it.
Who this comparison is for
Someone choosing between a new compact and a used crossover with a similar payment. Someone who can pay cash for a used car and wants to see whether a new-car loan is still cheaper after interest and depreciation. Someone replacing a paid-off car and trying not to confuse “no payment today” with “cheaper for the next five years.” Someone facing a large repair bill and asking whether to fix the car they have or replace it.
Related: true cost after the payment · same payment, different cost · affordability · lease vs buy.
FAQ
Is there a new car vs old car calculator? Yes. The CarAllIn calculator estimates one car at a time, so run it for the car you have and again for the new or used car you are considering, with the same years and miles. Compare net cost after resale. The results are planning estimates, not quotes.
What is the true cost of a new car beyond the sticker price? Add the loan interest, insurance, fuel or electricity, maintenance, registration and extras for every month you keep it, then subtract what you expect to sell it for. The true cost of car ownership guide walks through each line.
Does a longer loan term make a new car cheaper? It lowers the monthly payment, not the total cost. CFPB says a longer term means lower monthly payments but more interest over the life of the loan. See the longer loan term guide.
How do I calculate car ownership cost? Enter the price, down payment, APR, term, miles, fuel, insurance, maintenance, registration, years kept and resale percent in the calculator. It shows a monthly all-in figure, cash out, and net cost after resale.
Is a used car always cheaper to own? It often has a lower price and a milder early depreciation slope, but insurance, repairs, and fuel still decide the ranking. Run both sides.
Where do I put a repair I already know about? Add it to maintenance or extras on the used side for the year it will happen, or spread it across the keep period if you want a monthly view.
Should years owned match the loan term? Only if you will keep the car that long. A three-year keep on a six-year loan needs a remaining-payoff view.
Do sample model pages assume new or used? They load example inputs you can overwrite. Change price, miles, and condition-related maintenance to match the car in front of you.
Can I compare certified pre-owned to new? Yes. Use the CPO price and the maintenance you think the extra coverage is worth. Do not invent a warranty value you have not been quoted.