The map: One careful lady owner (you hope)

From oil leaks to dodgy accident repairs: how to tell if the used car you are buying really is all it appears. Michael Booth lifts the bonnet

According to the RAC, 97 per cent of drivers thinking of buying a used car are worried they'll be taken for a ride. Well, they should be. Over 80,000 complaints are made about used cars every year to the AA, RAC and trading standards authorities, and many are serious gripes about unroadworthy deathtraps and villainous dealers. But that shouldn't necessarily send you scurrying to your nearest new car showroom. Almost eight million used cars are sold in the UK each year and not all are dogs. And because new cars can depreciate by up to 50 per cent in their first year, buying second-hand can still make great financial sense, as long as you go armed with information on the car you're after, its value and the cost of spares and servicing. Steer clear of auctions (essentially casinos with a sheepskin dresscode), and if you're spending under pounds 2,000, dealers are best avoided, too (anyone working within those sort of margins will have to be buying very cheap). Instead, get hold of your local paper, Exchange & Mart or Autotrader; equip yourself with a torch, some hard cash and the know-how; and get ready to grab yourself a bargain.

Under the bonnet Engine oil An engine's oil can tell you as much about its health as a blood test can with a human. You want to see thin, light brown oil on the dipstick, not thick black tar with bits of metal in it.

Radiator With the engine cold, remove the radiator cap - you should see green or blue liquid with no oil floating on the top (which means oil and water are mixing and gasket catastrophe awaits).

Electrics Test everything methodically.

Clutch A high biting point or slipping clutch means a big bill approaches.

Gearbox Do the gears change without resistance or undue noise? Does it jump out of gear when accelerating? Does a shiny gear knob betray signs of high mileage?

Cylinder head Any especially loud rattles or taps here, while not as serious as

bottom-end noise, still mean the engine is at east in need of a tune, or badly worn. Pistons With the engine running remove the oil cap. Puffs of steam mean piston problems; an irregular idle can indicate a misfire. Bottom end Heavy knocking from the bottom end of a car's engine is usually terminal. Vehicle Identification number

Located on a metal plate in the engine bay and/or beside the driver's seat, should match up with paperwork. Engine Number

Stamped on the engine block - again should match paperwork, and watch for signs of tampering.

Pedal rubbers

A clue to mileage, but cheap to replace so not conclusive. Seats

Again, wear correlates to mileage. Mileometer

Every 1,000 miles taken off a car's mileometer adds around pounds 30 to its value; "clockers" make pounds 100m from their illegal activities each year. MOT certificates will verify mileage; in their absence check for unusual wear to the interior, that the digits on the mileometer line up, or for signs that the dashboard has been tampered with (ie worn screw heads). Steering

Is there playing in the steering, or does it feel unduly heavy? Take the car up to motorway speeds, if possible, to make sure there is no wheel shake.

Paint

It's better to see scratches and a little rust on a car over five years old than thick, glossy, new paint with the tell-tale overspray on window rubbers and in the engine bay - you never know what's lurking beneath. Boot

Lift carpets to spot rust or accident damage - revealed by welding or a crease in the boot floor.

Oil leaks

A reasonable amount of oil coating an old engine is fine, but if oil is forming on the ground beneath the car the motor is on its last legs.

Paperwork

A full service history (check with the garages) with MOT certificates adds 20 per cent to a car's value. Three hundred thousand stolen cars a year aren't recovered and they don't all end up torched in a field, so accept no excuses for a missing V5 registration document (check for a watermark). Call the previous owner (their address will be on the V5) to find out more, and if the car has had on average more than one owner every two years, be suspicious. One in seven used cars have been written off, the AA's Used Car Data Check (0800 234999; cost to non-members, pounds 25) will tell you if yours is one.

Accident damage

Between 21,000 and 28,000 unsafe cars are put back on the road each year after accident repairs - check for give-away uneven gaps between panels, welding on the underside of the car or mismatched paint. Filler Metal-based filler is undetectable by magnet. To spot it takes a keen eye - never inspect a car after dusk. Crouch by the headlamp and look down the sides of the car - any panel undulations mean a cheap repair. White powder in the engine bay or elsewhere - residue from filler sanding - is also a give-away. Rust

Surface rust is not always terminal, though great for haggling. But rust on sills, suspension mounts, cross members or seat-belt mounts will fail an MOT.

Exhaust

Blue or black smoke indicates engine wear; excessive grey smoke means the engine's oil and water are mixing.

Brakes

Take the car for a long test drive (at least 30 minutes), test the brakes to see if they pull to one side, feel spongy, fade under heavy braking or squeal.

Tyres

Check for uneven wear or bald spots indicating wonky tracking or locking brakes.

Suspension

Check the car sits straight (if it doesn't, the shocks are tired, or rust is weakening the structure); beware of car parked on uneven surface to disguise this.