BMW Z3 buyer's guide

A Z3 never rusts.

The body is far better than many rivals, but sills, door bottoms, the fuel tank and suspension arms can still corrode. On M cars especially, corrosion in odd places often points to old accident damage, so look carefully.

Any Z3 with an M badge is an M car.

M badges, wheels and bumpers are easy to fit. A genuine M Roadster or M Coupe has the 3.2-litre M engine and should be recorded as such on its V5C. Check the V5C and the engine bay, not the badges.

The boot floor problem only affects cars that have been on track.

Cracking around the differential mounts is more likely on hard-driven cars, but it is a known weakness of the M cars in general, and rear diff mount checks are worthwhile on six-cylinder cars too.

A full set of service stamps proves the car has been looked after.

The service indicator can be reset, so stamps alone mean little. Look for invoices that list the work done, with dates and mileages that make sense together.

Bodywork and structure

The Z3 shell is usually solid, but age, kerbs and accidents all leave marks. Take a torch, a magnet and a mat to lie on.

• Outer sills and front wings are bolted on and can rust or be scuffed; look at the sill bottoms and the wing edges behind the front wheels.
• Lift the carpets where you can and look at the floor near the sills and around the seat mounts for damp or corrosion.
• Door bottoms and the drain holes along them, which can block and rust from inside.
• Boot floor around the rear differential mounts, especially on M cars: lift the boot carpet and look for cracked, sunken or pulled spot welds and any welded reinforcement.
• Underneath, look at the corners of the differential mounting bracket and the rear subframe mounts for tears, fresh welding or fresh underseal over one area.
• Fuel tank and its straps, visible from underneath at the rear; damage or rust here is a costly job because the rear suspension has to come off.
• Panel gaps around the bonnet and bumpers, overspray on seals and mismatched paint, which point to accident repair. Corrosion in odd places is often a sign of a past crash.
• Coupe and M Coupe: check the tailgate, its seal and struts, and that the rear wiper works.

Engine

Most Z3 engines are durable when serviced properly, but cooling and valve timing need attention. Ask to see the engine started from cold.

• Coolant: it should be clean and at the correct level. Look for oil in the coolant and coolant in the oil, which suggest head gasket trouble after overheating.
• Cooling parts: the radiator, expansion tank, thermostat housing and hoses use a lot of plastic. Look for cracks, white crusty deposits and damp patches, and ask when the water pump and thermostat were last renewed.
• Temperature gauge should rise to the middle and stay there. A car that runs cool may have a thermostat stuck open; one that climbs in traffic needs explaining.
• Six-cylinder cars: a rattle at idle and weak pick-up at low revs can point to worn VANOS valve timing units. Oil leaks from ageing gaskets, and on M cars from VANOS seals, are worth looking for.
• Rough running or warning lights can come from camshaft or crankshaft position sensors, ask whether fault codes have been read.
• M cars: a persistent tick suggests valve clearances need adjusting, a job that is often skipped. Ask when it was last done.
• S54 M cars: ask whether the connecting rod bearings have been inspected or renewed, and look for invoices. Failure can destroy the engine.
• Check the oil on the dipstick or level gauge before the engine runs. Very low oil, sludge or a milky residue are warning signs.

Gearbox and drivetrain

The gearboxes and axles are generally strong, but mounts, linkages and fluids need checking.

• Manual gearchange should be precise. A sloppy, vague lever usually points to worn linkage bushes.
• M cars: a gear lever that leans towards fifth suggests a weak return spring or worn selector parts, and difficulty selecting first and second can point to clutch or selector problems.
• Clutch: check for slip under load and for drag, where gears are hard to select with the pedal down.
• Automatics should change smoothly without flare or harsh shifts. Ask whether the fluid has ever been changed.
• Rear differential: listen for whine that rises and falls with speed, and look for oil leaks around the casing.
• Clunks when taking up drive or lifting off can come from worn differential mounts, propshaft joints or rear subframe bushes.

Suspension, steering and brakes

The suspension is shared with the 3 Series of the time, so its wear points are well known.

• Front lower wishbones: worn ball joints and inner bushes cause vague steering and clonks.
• Rear suspension top mounts: a thump or clunk from the back over bumps is a common sign of wear, often felt from inside the cabin.
• Rear trailing arm bushes wear and can make the car feel unsettled under braking or over bumps.
• Tyres should show even wear across each tread. Heavy wear on one edge points to geometry problems, sagging springs or bent parts.
• Brakes: look for scored or corroded discs and check that the car stops straight. Seized callipers are common on cars that sit unused, including M cars.
• Handbrake should hold the car firmly on a slope; they are known to need careful adjustment.
• Look at the condition of the brake pipes underneath, and note any ABS warning light that stays on.

Hood, electrics and instruments

The hood is a large part of the car's condition, and the electrics are mostly shared with other BMWs of the era.

• Raise and lower the hood fully. On powered hoods, check that the motor works smoothly in both directions; faults can be costly.
• The plastic rear window cracks and clouds with age. Look for splits along the fold line and ask whether the hood has been replaced.
• Check the hood seals at the windscreen header and along the side windows, and the latches, which wear and let water in.
• Work the electric windows; they should rise and fall smoothly and seal against the hood or roof.
• Pull out the light switch and check the instrument and heater control lights work evenly.
• Warning lights for airbag, ABS and traction control should go out shortly after start-up.

Interior and trim

Interiors are well made, but age, sun and damp take their toll.

• Seats that rock on their runners under braking or acceleration point to worn mounting bushes.
• Leather wear on the driver's seat outer bolster is common and suggests higher mileage on cars that claim a low reading.
• Damp carpets and a musty smell mean a leaking hood, seals or door membranes.
• The glovebox lid often sags or will not close properly.
• Check the trim suits the car's specification, and note later swaps such as leather in a car built with cloth.

Paperwork and originality

With so many modified cars about, and with valuable M variants to copy, the paperwork matters as much as the car.

• Check the chassis number on the car and in the paperwork against the V5C, and confirm the engine size listed matches what is under the bonnet.
• Look for invoices, not just stamps: the service indicator can be reset. Dates and mileages should run in a sensible order.
• Check the MOT history online for mileage records and repeated advisories, such as suspension wear or corrosion.
• M cars: look for evidence of valve clearance checks, VANOS work, cooling system renewal and, on S54 cars, rod bearing work.
• Ask whether the boot floor or differential mounts have been repaired or reinforced, by whom and when, ideally with photographs.
• Note modifications such as aftermarket suspension, exhausts, wheels and engine tuning. Some are well regarded, but they should be declared to buyers and insurers.

What are the common problems with a BMW Z3?

Ageing plastic cooling parts, worn VANOS units on the sixes, worn front wishbone joints and rear top mounts, cracked plastic hood windows and leaking hood seals. On M cars, add cracking of the boot floor around the differential mounts and, on S54 cars, connecting rod bearing wear.

Which Z3 engine should I buy?

It depends on what you want. The four-cylinder cars are the simplest and most common. The 2.8 and 3.0 sixes are much quicker and smoother. The 2.0 and 2.2 sit between them. The M cars are in a different league for performance but need more specialist care.

Does the BMW Z3 rust?

Much less than many rivals of the period, but sills, door bottoms, the fuel tank and suspension arms can corrode. Rust in unexpected places often points to past accident damage.

What is the difference between pre- and post-facelift Z3s?

The 1999 facelift gave every non-M roadster the wider rear body, with new rear lights, boot lid and bumpers and interior changes. The engine range changed at the same time and again in 2000.

What is the M Coupe boot floor problem?

The floor around the rear differential mounts can crack or pull its spot welds, particularly on hard-driven cars. Lift the boot carpet and look underneath at the mounting bracket, and ask whether reinforcement has been fitted.

Is a BMW Z3 a good first classic?

For many people it is, because parts are easy to find and the cars are well understood by BMW specialists. A non-M car with a good history is the simpler starting point. Have an inspection done if you are unsure.

How can I tell a genuine M Roadster or M Coupe?

A genuine car has the 3.2-litre M engine, its own chassis number and its own specification. Check the V5C and the engine, and ask the BMW Car Club GB if in doubt.