Used car buying guide: BMW Z4 M

The Z4 M uses fly-by-wire throttle technology and VANOS variable timing. Issues with early BMW M3s (which shared the same engine) using the VANOS system had been resolved by the time it came along, and the engine is largely bombproof – although there are isolated cases of conrod bearing failure (it has insanely high piston speeds) and broken engine bolts caused by the car’s unyielding suspension. You’ll also encounter dire warnings about Z4 Ms missing their 1200-mile running-in service. It’s something to do with the oil being a cutting-in specification, but Smitheram disputes this. He says the oil Z4 Ms left the factory with was the standard spec and that the issue was a warranty one rather than anything to do with engine health. As evidence, he points to his own car, which had its running-in service at 4000 miles and hasn’t missed a beat. 

Whatever the truth, the Z4 M remains a thoroughbred, with the running costs to suit. Sellers describe it as a classic. That’s a seductive notion but, with 35 currently available across all price points, have your haggling boots laced up tight. 

How to get one in your garage: 

An expert’s view...

DAVID SMITHERAM, BMW CAR CLUB OF GREAT BRITAIN “I own a 2006 Roadster that’s done 55,000 miles. I work in motor racing and for many years saw how fast and reliable the old M3 E46s were and how easily they doubled as road and track cars. It got me thinking about the Z4 M, the last BMW sports car with a manual gearbox and a naturally aspirated straight-six. Mine’s a Roadster, so I’m bound to say it’s the one to buy, but since the car was designed as an open-top, it feels almost as stiff as the CoupeÃ. Prices are softer too, and it’s more fun in the sun.” 

Buyer beware... 

ENGINE OIL and filter change every 7500 miles would be nice to see. Initial running-in service not as crucial as claimed as long as subsequent services are kept up. Inspection II service requires valve clearance check. Some cases of failed conrod bearings beyond 75k miles. Budget for toughened replacements as a precaution. If idle is lumpy, check and clean idlec ontrol valve. Check condition of engine mount bolts, which have been known to fracture. 

SUSPENSION AND BRAKES Rear trailing arm bushes begin to wear at 50k miles, leading to uneven tyre wear; front bushes give less trouble. Rear springs can snap – fit thicker, lower Eibach replacements. Ride is unaffected because it’s already rock-hard. Brakes can feel dead but aftermarket pads fix it. Standard pads are okay on road but not for track use. 

BODY On Roadsters, crouch down, find the roof drain holes and check for blockages. A wire coat hanger should clear obstructions. On CoupeÃs, check for corrosion on the underside of the bootlid caused by water collecting in the scoop between it and the rear window. Poor accident repairs aside, it’s the only place Z4 Ms rot. Check rear centre brake light works (its securing screws are often too tight). 

INTERIOR Expect wear on door handles, switches and driver’s side seat bolster, and check electric windows work (regulators can be troublesome). 

Also worth knowing:

BMW protected the roadster’s roof motor in a watertight container (it’s on the passenger side of the car) but if the roof’s drain holes become blocked, water enters it and the motor packs up. Fortunately, those clever blokes at the BMW Car Club have a fix that involves relocating it out of harm’s way. 

How much to spend:

£12,000-£13,495 - Private-sale 2006 Roadsters with 90k-plus miles start here, although guide auction price for average cars at this age is around £7000. 

£13,995-£15,495 - Still strong money for 06- and 07-plate Roadsters with mileages around 65k.