What should I check before I even start the engine?

Make sure the engine is stone cold, then watch that every warning light comes on with the ignition and goes out. Check tyre tread, fluid levels and the oil filler cap while you're there.

What does a droning noise at 50-70mph usually mean?

A wheel bearing, most often. It changes as you load the steering left or right. A whine that's there in every gear points somewhere pricier, like the gearbox.

How long should a used car test drive be?

At least 20 minutes, mixing town traffic, a dual carriageway stretch, a three-point turn and some full-lock turns. Short drives hide faults that only appear once the car is properly warm.

Which warning lights mean I should walk away?

If the engine management, ABS, airbag or DPF light stays on after start-up, that's a deal-breaker. So is a car where those lights never illuminate at all.

The Pre-Purchase Test Drive Checklist: What to Check and Listen For

You can learn more about a used car in twenty minutes behind the wheel than in an hour of walking round it on the driveway. Paint hides a lot. A test drive doesn’t. And the difference between a good buy and a money pit is usually something you could have heard, felt or spotted if you’d known what to look for.

Here’s how to run a test drive properly, step by step.

Before You Turn the Key

Turn up early and unannounced if you can, or at least make sure the seller knows you want the car cold. A car that’s already warm when you arrive is a red flag — it can hide a rough cold start, a puff of blue smoke or a rattle that disappears once the oil is up to temperature.

While it’s still cold:

Check the tyres cold. Tread depth, uneven wear across the face, cracking on the sidewalls, and whether all four are a matching brand. Four odd budgets on a car that supposedly has a full service history tells you something.
Look at fluid levels. Oil that’s black and thin, coolant that’s murky, or a screenwash reservoir bone dry suggests a seller who hasn’t been fussy.
Undo the oil filler cap. Mayonnaise-style sludge underneath points to a head gasket issue or lots of very short journeys.
Check the VIN on the windscreen base against the logbook, and look for overspray on rubber seals and bolts — a hint at accident repair.

The Cold Start

This is the single most revealing minute of the whole process. Stand behind the car while it starts.

A brief puff of white vapour from a diesel on a cold morning is normal. Persistent white smoke that hangs around usually means coolant is getting somewhere it shouldn’t. Blue smoke is oil burning — valve stem seals or worn rings. Black smoke under acceleration on a diesel is often just a clogged EGR or a hard-driven car.
Listen for rattles. A metallic rattle for a second or two on start-up can be a timing chain tensioner on its way out — a £700 to £1,500 job on many cars.
Ticking from the top of the engine is often just noisy injectors or a tired hydraulic lifter, but it’s worth noting.

Warning Lights: The Ones That Must Go Out

With the ignition on and the engine not yet running, every warning light should illuminate. That’s the bulb self-test. If the engine management, ABS, airbag or DPF light never comes on, someone has probably removed the bulb — walk away.

Once the engine starts, they should all go out within a couple of seconds. Any that stay on are either a straightforward sensor fix (£80 to £150) or the tip of something much bigger. Don’t let a seller tell you it’s “just a sensor” unless they’ll knock the diagnostic cost off the price.

The First Five Minutes: Low-Speed Checks

Start on quiet roads before you hit anything fast.

Steering Play and Pulling

With the car rolling slowly, turn the wheel a couple of centimetres each way. There should be almost no slack before the front wheels respond. Noticeable play, a vague feeling on centre, or a clonk over speed bumps points to worn track rod ends, a tired steering rack or perished bushes — typically £100 to £400 depending on what’s gone.

On a straight, flat road, take your hands off the wheel briefly (safely, obviously). The car should track straight. A steady pull to one side suggests an alignment issue, a binding brake or, worse, accident damage that was never properly repaired.

Brakes

Find a safe, empty stretch and brake firmly from around 40mph.

Pulling to one side under braking usually means a sticking caliper or a warped disc.
A pulsing pedal is almost always a warped disc.
Grinding or a metal-on-metal scrape means the pads are down to the backing plates.
A long, spongy pedal could be air in the system or a failing master cylinder.

Do a three-point turn while you’re at it, and use full lock both ways — that’s when you’ll hear a worn CV joint clicking.

Noises at Different Speeds

Faults tend to announce themselves at particular speeds, so vary your pace deliberately.

Under 20mph over bumps: knocking or rattling is usually drop links, anti-roll bar bushes or top mounts. Cheap-ish — £60 to £200 fitted per corner.
30 to 50mph whine: could be gearbox or differential. A whine that’s there in every gear and changes with road speed rather than engine revs points away from the engine.
50 to 70mph drone: classic wheel bearing. Test it by gently loading the steering left then right — if the noise changes, that’s your culprit. Around £150 to £350 fitted.
Vibration at 60 to 70mph: wheel balance or a buckled alloy first, a worn driveshaft or engine mount second.

Get on a dual carriageway or motorway if you can. That’s where gearing, wind noise and any high-speed shimmy will show up, and where you’ll find out whether sixth gear actually engages cleanly.

Things People Forget to Test

The clutch bite point — high and vague suggests a clutch on its way out, £600 to £1,200 fitted.
Every gear, including reverse, and the handbrake on a slope.
Air conditioning — it should blow genuinely cold within a minute. A regas is £60 to £120, but a failed compressor is £400 upwards.
Heated seats, windows, mirrors, infotainment, parking sensors, reversing camera — all the toys that cost real money to fix.
Stop somewhere and let it idle for five minutes. Watch the temperature gauge creep up, and look underneath for fresh drips.

After the Drive

Leave the engine off for a moment, then check the oil and coolant again. Then look at the ground where the car was parked before you set off — a fresh patch of oil, coolant or transmission fluid is a very expensive clue.

If you can, take a mate who knows cars. Two sets of ears catch twice as much, and one of you can drive while the other listens from the passenger seat.

Red Flags That Mean Walk Away

Engine management, ABS, airbag or DPF light staying on.
A seller who won’t let you start it cold, or insists on driving it first.
A test drive restricted to a five-minute loop round the block.
Vagueness about service history, or an MOT advisory list that’s grown every year.
A car that’s had an MOT or tax gap that doesn’t match the story you’re being told.

The Test Drive Checklist

Car is cold when you arrive.
All warning lights illuminate, then go out.
No smoke from the exhaust once warm.
No rattles on start-up.
Steering has minimal play, no clonks on bumps.
Tracks straight with no pulling.
Brakes don’t pull, pulse or grind.
Every gear engages cleanly, clutch bites sensibly.
No drone, whine or vibration up to motorway speed.
All electrics, air con and toys work.
No fresh leaks after idling.
20 minutes minimum, mixed roads.

What Faults Cost

Rough fitted prices so you can price the risk into your offer: drop links £60 to £200 per corner, ABS sensor £80 to £150, wheel bearing £150 to £350, brake caliper £150 to £300, air con regas £60 to £120, clutch £600 to £1,200, timing chain £700 to £1,500, and a new set of decent tyres £320 to £800.

If the seller won’t move on price to cover a genuine fault you’ve found, that’s your answer.

The Takeaway

Book the test drive for a cold morning, give it at least 20 minutes across town roads and a fast stretch, and treat every noise as a question you’re allowed to ask. A confident seller with nothing to hide won’t mind a bit. A nervous one will, and that’s useful information too.

When you’re ready to make the change, it’s worth having a look at UpCars.uk — the cars there are checked over properly before they’re listed, which takes a lot of the guesswork out of that first cold start.