Comparing Cars Without Paying for Three Full Checks

Three cars, and you can't inspect them all

Comparing cars is a filtering problem, not a research project. It sits at the sharp end of buying a used car. You've found three cars that look right on paper. Two of them will turn out not to be, and you'd rather find that out from your sofa than from a two-hour drive.

The instinct is to run a full check on all three. It feels thorough, but it's the wrong order. Most of what eliminates a car is free, and the detailed evidence only starts earning its cost once a car is a serious candidate.

Work in passes: cheap and wide first, expensive and narrow last.

Pass one: free, on everything

Run a free check on every registration on your list. It costs nothing, so there's no reason to be selective at this stage.

You're looking for the MOT history, and for patterns rather than individual failures. A car that failed once on a bulb is fine. A car whose advisories keep naming the same corner of the suspension is telling you what the next bill looks like.

Three things take a car off the list here, before you've spent anything:

• A recorded mileage that drops between tests, or barely moves for a year and then jumps (our guide to what mileage is too high covers the patterns)
• A run of structural advisories: corrosion, subframes, mountings
• A gap where an MOT should be, on a car that was supposedly in daily use

Any of those, and you can stop. You've saved the afternoon and the check fee.

Pass two: identity, on the survivors

With two cars left, the question changes from "is anything obviously wrong" to "is this car what the advert says it is".

That's keeper history, plate changes and import records. None of them are in the free public data. It's the pass most people skip, and it's the one that catches the mismatch between the car on paper and the car in the photos.

You're not buying certainty here. You're getting enough to know which of the two is worth driving to see, and which of the questions to ask matter most when you get there. If you're weighing several cars, this is also where a free allowance runs out. It's built for checking a car, not a shortlist.

Pass three: the full evidence, on one car

By now you have a car you intend to buy. This is where the full check earns its money, and it's the only point where it does.

Outstanding finance, stolen markers and write-off categories aren't in anything free, and they're the three findings that cost you after you've paid rather than before. They don't show up on a test drive. They don't improve because the car drives nicely.

One full check on the right car beats three on cars you were never going to buy. That's the whole argument for doing it in this order.

What none of these passes tell you

Condition, because every check in this sequence reads records, and records don't hear a wheel bearing.

A car can have a clean history, honest mileage and a full set of markers in its favour, and still need work you'd only have found by driving it. The checks narrow your shortlist. The inspection decides.

It's worth keeping the money in proportion too. Running costs between two similar cars can differ by hundreds a year. Our own guide puts an ordinary used car at roughly £2,500 a year at the modest end, climbing to £5,000 or more before depreciation. A difference that size outlasts anything you save on checking.

Common questions