Man Maths: BMW Z4 M Coupé

It all starts with that engine, the legendary S54 3246cc straight-six from the E46 M3. Singing to 338bhp at a giddy 7900rpm, it made the larger flat-six’s lower output in the contemporary Porsche 911 Carrera (first-generation 997) look decidedly indolent.

And then there’s that gorgeous Bangle body. Something that absolutely no-one said at the time, but doesn’t the Z4 coupe look better with every passing day? Its skunkworks predecessor, the Z3 M Coupe remains an acquired taste (hence the ‘clown shoe’ nickname), but somehow that long bonnet, wide haunches and double bubble roof look just right on the Z4 M.

Let’s talk about the steering. BMW binned off the electrically assisted rack of lesser Z4s and stole the hydraulically-assisted rack from the M3, along with its gearbox, brakes, rear axle hardware and differential. Not to mention that engine. In the lighter body of the Z4, acceleration was even more savage than the M3 – Auto Express recording 4.7 seconds to 60mph – with manual gears, no launch control and state-of-the-ark tyre tech – while de-restricted examples reportedly saw north of 170mph.

Those press criticisms in period – a choppy ride, heavy handed traction control (just turn it off…?), and spiky behaviour beyond the limit – are now all part of the unruly character we actively search out as the Yin to the bland Yang of modern cars. A point not lost even 20 years ago, when CAR Magazine described the Z4 M Coupé as ‘a TVR for people who haven’t got time to spend hanging around hard shoulders’. And if we’re being honest with ourselves, don’t we all need just a soupçon more TVR in our motoring lives?

And if you’re still not convinced, let’s take a look at the production numbers. BMW made approximately 20,000 E46 M3s in right hand drive. But only 578 Z4 M Coupés ever came to the UK – less than half the number of F40s that Ferrari built.

How much will this super-exclusive slice of thoroughbred BMW M-car set you back? Far, far less than you might think. The lovely example in the pictures sold a few weeks ago through Bring a Trailer’s UK auction site for £16,003. At 71,000, the mileage was entirely reasonable and anyone who thought these well-chosen mods diminished the value had missed a trick.

The Eventuri carbon air intake adds a delightful induction bark to the S54, while the Z4-specific Bilstein dampers and Eibach springs are higher specification than the OE originals and would no doubt sharpen up the handling a treat. Swap the 19in wheels out for the original 18s, in the interests of ride and general usability, and the Eibachs’ 30mm drop in ride height will still gobble up the arch gap.

Now this wouldn’t be a Man Maths story without some impending peril, and fear not, for the S54 has laid waste to many an unsuspecting enthusiast’s wallet. At this kind of mileage, four apocalyptic horsemen are just cresting the horizon and headed in your very direction: rod bearing roulette, VANOS rattle, valve clearance drift, and throttle actuator disintegration.

The good news is that all are resolvable, but you would be advised to get spending pre-emptively on all counts. Particularly on account of the rod bearings, where failures spell a grisly death for the straight-six. A specialist will charge you in the region of £1800 for a complete replacement, along with fresh engine mounts whilst you’re in there.

The problem with the VANOS (BMW’s variable valve timing system) is that the oil pump disc has oversized holes for the drive tabs on the exhaust camshaft hub, which causes rattles and can break the tabs. The O-rings in the seals also harden and leak over time, sapping performance. Factor in £1000 for new seals, oil pump disc and labour.

The S54 uses solid shim-and-bucket valve operation, so the clearances need checking periodically – a job usually left for the next owner. Reckon on £500, but do it with the VANOS work (when the cam cover is already off) and you might halve that. And as for the throttle actuator’s failing gears, allow £600 for a replacement actuator – but repair is possible and might cost half that.

All in all, then, imagining you were lucky enough to snap up this lovely example, budget on £20,000 for a well sorted, future-proofed, rare as hen’s teeth M car. Its parts commonality with the M3 delivers fuss-free maintenance with specialists aplenty, but you also get those looks, a 75kg weight saving and Ferrari-trumping exclusivity.

Factor in possible appreciation of values (a combination of that rarity, the legendary engine and the hot 2000s sector generally) and your financial justifications need no further wrangling.

So who cares if a road digger is more fun? A poverty-spec JCB 3CX will cost you £83,280, only does 9mpg and won’t even have the decency to fit in your garage. Not even Clarkson could make the Man Maths work on that.

Photography by Jordan Butters

The Bring a Trailer auction featured in the story can be found here