5 things to check before buying a used car (that nobody tells you).

Most buying guides will tell you to check the tires, the bodywork and the service book. They are right, but every used-car buyer already knows that. The cars that go wrong six months after purchase rarely fail those obvious checks. They fail the quiet ones, the ones a quick walk-around won't catch unless you know to look. Below are the five we run on every single car that arrives at our showroom in Leeuwarden, in roughly the order we run them.

1. Always insist on a cold start

If the engine is already warm when you arrive, it's not necessarily a scam, but you've just lost the single most informative test you can run on a used car. A cold start exposes worn injectors, dying glow plugs, leaky valve seals (puff of blue smoke at first ignition), failing starter motors and dodgy battery health all in the first ten seconds. Politely tell the seller you'd like to come back, or arrange a viewing first thing in the morning. Any honest seller will agree.

What you're listening for: an even, immediate fire-up with no extended cranking. What you're watching for: anything more than a faint puff of vapour from the exhaust on a cool morning. Blue or grey smoke that lingers means oil getting where it shouldn't.

2. The dashboard dance

When you turn the ignition to position II (without starting the engine), every warning light on the cluster should illuminate, then go out one by one as the car runs its self-test. This is the dashboard telling you which sensors are still alive.

If a light is missing entirely, most often the airbag, ABS or engine management lamp, it has been physically removed from the cluster. We've seen tape, paint and even tiny strips of black PVC over the bulbs. It's almost always hiding a fault someone didn't want to fix.

3. Pull the oil cap

Twist off the engine oil filler cap and look at the underside. You're checking for two things: a creamy, mayonnaise-like residue (a head-gasket warning sign, coolant getting into the oil), and excessive carbon sludge (skipped service intervals). A clean cap with golden-honey oil underneath is what you want. Black-but-clean is fine for higher-mileage cars; black-and-gritty isn't.

While you're under the bonnet, glance at the coolant reservoir. The fluid should be pink, blue or green depending on the manufacturer, never brown, never with an oily sheen on top.

4. Check the VIN matches in three places

Every European-registered car has its VIN (chassis number) in at least three places: stamped into the body (usually under the windscreen, sometimes also under the bonnet or in the boot), on the manufacturer's plate (a metal sticker, often on a door pillar), and in the registration document. All three must match, character for character.

If one is missing, scratched, replaced with a printed sticker, or doesn't match the others, walk away. We don't mean "ask the dealer about it." We mean leave. A mismatched VIN is the single most common signature of an insurance write-off being passed off as a clean car, or worse.

5. Look under the car, not just at it

Most buyers never crouch down. Spend ninety seconds doing exactly that, both at the front and at the rear. You're looking for fresh wet spots on the ground beneath where the car has been parked, glistening damp on the underside of the engine or gearbox, and rust on suspension components, particularly on the springs and the rear subframe mounts.

A small, dry, crusted oil weep on a 10-year-old engine is normal. A wet, fresh leak is not. If the seller has just power-washed the underside and everything is suspiciously clean and shiny, that itself is a signal.

Used cars don't lie. Sellers do, occasionally, but the car itself is incapable of it. Every fault leaves a trace. Your job is just to know where to look.

A bonus: ask for the last receipt

Not the service book, not the MOT history, the most recent receipt for any work done. A genuine seller of a well-kept car will have one in the glovebox and be proud to show it. Vague answers ("it was done somewhere down south") are vague for a reason.

None of these checks require expertise. None of them take more than ten minutes combined. And every single one of them has saved a customer of ours, at some point, from a five-figure mistake. Run them every time. Or, easier still, let us run them for you. Every car on our floor has been through this list (and a much longer one) before it gets there.