Be honest with the numbers - the tool is only as truthful as what you feed it. For the repair figure, total everything due in the next six months, not just today's quote.
The Reasoning
This is honest guidance from real workshop experience, not financial advice. It cannot see rust, service history or how the car has been treated - if the decision is close, a £50 independent inspection is the best tiebreaker money can buy.
How the Calculator Thinks
The trade's classic yardstick is the 50% rule: when one repair costs more than half the car's working value, think hard. It is a decent instinct and a terrible law - because it ignores everything else that matters. A £900 gearbox in a rust-free, full-history car you plan to keep for years is a different decision from the same £900 in a tired car you were already going off. So the tool starts with the repair-to-value ratio, then adjusts for mileage, age, overall condition and - the one everyone forgets - how long you actually want to keep the car. Then it shows its reasoning, because a verdict you cannot interrogate is just someone else's opinion.
The Case for the Devil You Know
Here is the part the "just scrap it" crowd misses: the money you do not spend repairing this car does not buy you a perfect car. It buys you a different used car - with its own age, its own wear, and a service history you have to take on faith. A meaningful share of used cars change hands precisely because a bill was coming; some of that deferred maintenance lands on the new owner in year one. Your repaired car, by contrast, is a known quantity: you know how it has been driven, what has been done, and after this repair, the biggest looming bill is behind it. That knowledge has real cash value, and the calculator quietly credits it.
When Selling Really Is the Right Answer
- The repair costs more than the car. Over 100% of value, you are not repairing a car, you are buying it back from the dead - and the next fault arrives regardless.
- This is the third big bill in a year. Repeated four-figure repairs are a car telling you something. Believe it.
- Structural rust is involved. Mechanical parts can be replaced forever; a rotten shell cannot. Rust is the one fault that genuinely ends cars.
- You were leaving anyway. If you planned to change the car within months, put the repair money towards the next one and sell this one honestly with the fault declared - the trade fixes cheaper than you can.
- The fault will recur by design. A DPF on a car that only does school runs will block again - see our DPF cost guide. Fixing it without changing the pattern is renting the repair, not buying it.
Getting the Two Numbers Right
The value: look up what your exact car - year, engine, trim, mileage - actually sells for, not what optimists ask. Auction and part-exchange values sit lower than private sale prices; a realistic middle figure is what the tool wants. The repair: get it itemised and, over £500, get a second quote - our repair cost guides show what a fair price looks like for a clutch, wet belt, cambelt, timing chain, DPF or injectors, and the questions that keep a quote honest. And add up everything due in the next six months, including MOT advisories - that total is the honest number the decision rests on.
Sunk cost pulls both ways. "I've already spent £2,000 on it this year" is not a reason to spend more - that money is gone either way. But "I hate this car anyway" is not analysis either. The fair question is only ever about the future: from today, is the cheapest reliable motoring the repaired car you know, or a replacement you do not? Run the numbers, read the reasoning, then decide with a clear head.
