Is the old rule true — replace the car if the repair costs more than it's worth?

It is a slogan, not arithmetic, and it fails in the direction that costs you money. A $2,300 repair on a car worth $4,000 sounds absurd until you price the alternative: a replacement carries sales tax, title and registration, an inspection, and its own depreciation, and every one of those is cash you spend to arrive at a car you also do not know. The comparison that decides it is cost per month of keeping versus cost per month of replacing, over the same number of months. Sometimes that still says sell. It says so for reasons you can show someone.

Could the repair I was just quoted actually be free?

Three things are worth checking before you approve any estimate. An open recall is remedied at no charge, though 49 U.S.C. 30120(g) withdraws that free-remedy requirement once the vehicle was first bought more than 15 calendar years before the recall notice. The federal emissions performance and defect warranties under 40 CFR 85.2103 run 8 years or 80,000 miles on specified major components — catalytic converters, particulate filters, the emission control module, and on a diesel the exhaust gas recirculation components — and 40 CFR 85.2102(a)(8) defines the covered owner as the original purchaser or any subsequent purchaser, so it follows the car to you. And if a vehicle service contract is in force, the claim goes in before the wrench turns, not after.

How many more miles will the repair actually buy?

Nobody can tell you, and any number that arrives with confidence should make you suspicious. What you can do is refuse to be optimistic on paper: pick a horizon short enough that you would accept being wrong — 24 months is the one I use — and require the decision to survive at that horizon. Then run it a second time with one additional repair of the same size budgeted in. If the answer flips between those two versions, the estimate never was the deciding number.

Where can I get a free value figure for my own car?

There is no federal database of vehicle values; the well-known valuation sites are commercial and their numbers are estimates, not quotes. The closest thing to a hard figure is an actual written offer from a dealer or an online buyer, which costs nothing to obtain and is a number someone is willing to stand behind. The Bureau of Labor Statistics does publish the used cars and trucks price index (series CUUR0000SETA02), which tells you which way the whole market is drifting but nothing about your car.

Repair or Replace: The Worksheet I Run Before I Pay

The transmission estimate came to $2,340 — parts, labour and tax on one sheet handed across the counter. I did with it what almost everybody does. I held it up against my bank balance, and then I held it up against what the car was worth, and somewhere in that second comparison I had already half decided to replace the thing. Both comparisons were the wrong one, and the second was wrong in the direction that costs money.

The car's value is not what you are buying when you approve a repair. You are buying months. Below is the worksheet I fill in instead, and the three checks that come before any of the arithmetic.

One limit before we start. The figures and the warranty sections here are for gasoline and diesel cars. An electric drivetrain fails in different places and carries its own battery warranty terms, which is a separate piece of reading and not this one.

Before any arithmetic: three things that might make the repair free

Run these first, because each one changes the number at the top of the worksheet rather than the math underneath it.

An open recall. Check the VIN at NHTSA's recall lookup. The free remedy is not open forever: 49 U.S.C. § 30120(g) (read 18 August 2026) says the no-charge requirement does not apply if the vehicle "was bought by the first purchaser more than 15 calendar years... before notice is given." Fifteen years from first sale, measured against the notice date — not from today, and not from when you bought it.

The federal emissions warranty. This is the one that goes unclaimed. I pulled Subpart V of 40 CFR Part 85 from the eCFR versioner API (2026-08-01 edition, read 18 August 2026). § 85.2103 sets the light-duty performance warranty at 24 months or 24,000 miles — "except that the warranty period is 8 years or 80,000 miles for any nonconformity resulting from a failed specified major emission control component." That sentence is paragraph (c)(1); the components themselves are listed one paragraph down, in (d)(1) — catalytic converters and SCR catalysts and related components, particulate filters and traps, the emission control module, and, on a diesel, the components related to exhaust gas recirculation. The section was last amended at 91 FR 7759 on 18 February 2026, so it is current as of this writing.

Two details make this worth ten minutes. § 85.2101 applies §§ 85.2101 through 85.2111 to all 1981 and later model year vehicles subject to Part 86 Subpart S. And § 85.2102(a)(8) defines "owner" as "the original purchaser or any subsequent purchaser of a vehicle" — the coverage is attached to the car, not to the person who bought it new. A catalytic converter quote on a six-year-old car with 71,000 miles is a conversation with the manufacturer before it is a conversation with your wallet.

A service contract still in force. If one exists, the claim goes in before the repair starts. Almost every contract requires prior authorization, and a shop that has already opened the engine has handed the administrator a clean reason to deny.

The seven lines

Write them down. The point of putting it on paper is that it exposes which single assumption is carrying the decision.

Repair, out the door. Parts, labour, shop supplies, tax. Include the diagnostic fee even if it is already spent.
Free-repair offsets. Recall, emissions warranty, service contract. Subtract.
Net repair = line 1 minus line 2.
Horizon. Months you require the repaired car to serve. Pick a number you would accept being wrong about.
Cost per month of keeping = (net repair + fuel + insurance + registration + a reserve for the next failure) ÷ horizon.
Cost per month of replacing = (purchase price − realistic resale at the same horizon + sales tax + title and registration + a pre-purchase inspection + its fuel and insurance) ÷ horizon. Add whatever your current car brings as a trade or private sale, as a subtraction.
Compare 5 and 6. Then change one assumption and see whether the answer moves.

Running it on a 2013 wagon with 168,000 miles

Take the estimate above on a 2013 Subaru Outback, the 2.5-litre CVT. Its EPA figures are public: fueleconomy.gov rates that configuration at 26 mpg combined and puts annual fuel at $2,350, against $3,100 for the 3.6-litre six of the same year. Those are EPA's own numbers at their own assumed mileage and fuel price, which makes them a fair basis for comparing two cars and a poor basis for predicting your own bill.

Keeping, over 24 months: $2,340 net repair, roughly $4,700 of fuel, plus insurance and registration. That is about $293 a month before the fixed costs.

Replacing with a $14,000 car, over the same 24 months: sales tax at 6% is $840, title and registration call it $200, and I would not skip an inspection — hiring an independent one is a couple of hundred dollars against a five-figure decision. Say the replacement is worth $11,000 in two years. That is $3,000 of depreciation plus $1,190 of transaction cost plus the same $4,700 of fuel: about $370 a month.

Keeping wins by roughly $77 a month. Now add one line — a reserve for a second failure the same size as the first, on a car with 168,000 miles on it. Keeping becomes about $391 a month and loses.

That is the whole exercise. The decision was never sitting in the $2,340. It was sitting in whether you believe one more repair is coming, and in the resale figure you invented for a car you have not bought. Two assumptions, both yours, both arguable. The estimate was just the thing that started the argument.

Two inputs above are placeholders and should not survive contact with your own paperwork. The 6% sales tax is an example rate: Texas charges 6.25% of the sales price less any trade-in allowance, and on a private-party purchase the taxable figure may be the state's standard presumptive value rather than the amount you handed over, per the Texas Comptroller (read 18 August 2026), which prices a gift at $10 and an even exchange at $5. Title and registration are the other one, often set county by county. Both belong to the state you will register in, not to me.

Is this failure a pattern, or did you get unlucky?

Line 5's reserve is a guess unless you check whether the part that broke is a known weak point. NHTSA's complaint database answers that for free, and it answers by model rather than by VIN.

The public API takes a plain query. For that 2013 Outback:

https://api.nhtsa.gov/complaints/complaintsByVehicle?make=subaru&model=outback&modelYear=2013

I ran it on 18 August 2026 and it returned 296 complaints, the largest groups being ENGINE (44), POWER TRAIN (36), AIR BAGS (29), and STEERING (27). You can read the same thing through the search form at nhtsa.gov/recalls if you would rather not touch a URL.

Read it for shape, not for score. These are unverified consumer submissions — anyone can file one, nobody confirms them, and popular models collect more of everything simply because more of them exist. What the file is good for is the second question: does the component on your estimate show up as a cluster with a consistent story, or is it a scatter? A cluster means budget for the reserve. Absence means very little, because most failures are never reported to anyone.

What 2026 is doing to both sides of the comparison

Three federal price series, all pulled from the BLS public API on 18 August 2026, comparing July 2026 with July 2025 (U.S. city average, not seasonally adjusted):

Series	Index, Jul 2026	Year over year
Motor vehicle maintenance and repair (CUUR0000SETD)	460.185	+6.6%
Used cars and trucks (CUUR0000SETA02)	184.661	−1.9%
Gasoline, all types (CUUR0000SETB01)	350.846	+24.6%

You can pull these yourself from the BLS databases. Repair got more expensive, used cars got slightly cheaper, and fuel moved hard enough that the IRS raised its business standard mileage rate mid-year — 72.5 cents for January through June 2026, then 76 cents from 1 July, per the IRS rate page (read 18 August 2026). That rate is a tax convention, not your cost per mile, and using it as a running-cost figure will overstate an old paid-off car by a wide margin.

What the table means for the worksheet: line 6 got a little friendlier, line 1 got worse, and the mpg gap between your car and the replacement is worth about a quarter more than it was last summer. If the two cars burn the same fuel, ignore the last row entirely.

If they do not, rebuild that row on the price you actually pay at the pump. EPA's $2,350 and $3,100 are computed at 15,000 miles a year, 55% city and 45% highway, and the fuel price fueleconomy.gov is currently loaded with (read 18 August 2026), which is a fair way to rank two cars and a poor way to predict a household. EIA put the national average for regular at $4.006 a gallon in the week ending 10 August 2026 (weekly retail prices, read 18 August 2026): at that price, 15,000 miles at 26 mpg combined burns about 577 gallons, near $2,310, and a replacement five mpg thirstier costs roughly $550 a year more. Drive 8,000 miles instead and the whole row shrinks by nearly half, which is how a fuel-economy gap that looks decisive stops deciding anything.

The two lines people fill in backwards

Line 4 and line 6, almost always in the same direction.

The horizon gets stretched. "This fixes it for another four years" turns a $2,340 repair into $49 a month and wins every argument, which is exactly why it should not be allowed to. Four years is 48 months of not knowing anything about a car with 168,000 miles on it. Twenty-four is defensible.

The resale figure gets flattered. People price the replacement at what they hope to get back, which quietly moves several thousand dollars from the replace column to the keep column, or the reverse if they are talking themselves into a purchase. There is no federal source for vehicle values — the valuation sites are commercial and produce estimates, not offers. A written offer from a dealer or an online buyer costs nothing and is a number someone will actually honour.

One more piece of context for line 4, and it needs its date attached. In a release dated 21 May 2025, S&P Global Mobility put the average age of US light vehicles at 12.8 years, and passenger cars alone at 14.5. They update that annually, and I found nothing newer on their press site when I looked on 18 August 2026 — so treat 12.8 as the 2025 reading rather than today's, and check for a later one before you quote it at anybody. Either way the shape holds: a high-mileage car is not an outlier, the fleet is full of them, kept running by people doing this arithmetic and deciding to fix it.

Project your own annual mileage from your own odometer, though — two inspection reports or two oil change receipts will give you the number. The figure that circulates instead is 13,476 miles a year, and it deserves less trust than it gets on two counts: it is per driver rather than per vehicle, and it comes off an FHWA table built on survey work from the 1990s.

When the worksheet loses on purpose

There are three cases where I would not let the arithmetic decide.

A frame, airbag, or brake problem is a stop, not a line item. If the inspection that produced the estimate flagged structural damage, the question stopped being financial. The same goes for a salvage or rebuilt title you did not know about, which will show up in the title record long before it shows up in the driving.

A car you cannot legally register is worth nothing to you regardless of the math. If it will not pass your state's emissions test and the failing component is out of the 8-year/80,000-mile window in § 85.2103, the repair is not optional and the comparison collapses to: fix it, or sell it as-is and disclose.

And if the replacement is not actually identified — if it is a $14,000 idea rather than a specific car you have driven and had inspected — then line 6 is fiction, and a fiction with a number in it beats a real estimate every time. Find the car first. Then run the sheet.

Whichever column wins, the transfer paperwork is indifferent to your reasoning. Sell, and the odometer disclosure at 49 CFR 580.5 still travels with the title: the reading at transfer, both names and addresses, and a signed certification that it is the actual mileage, or beyond the odometer's mechanical limit, or not actual. The age exemption arrives later than most private sellers expect — under § 580.17 a model year 2011 or newer vehicle is exempt only once it is transferred at least 20 years after 1 January of its model year (read 18 August 2026), which keeps a 2013 car inside the rule into 2033. Keep the estimate and the filled sheet either way; if a second failure turns up, line 5's reserve stops being a guess.