BMW Z4 M Roadster 2006 Review - International

International launch review

OVERVIEW
Remember the glut of MTV shows more than a decade ago in which rock bands turned off their amplifiers, picked up their acoustic guitars and plonked themselves in front of the cameras to record what were called 'Unplugged' sessions? After discovering with amazement that decibels weren't always important for entertainment and that Kurt Cobain could hold a tune, punters dragged the accompanying CDs off record store shelves in box loads.

It might be drawing a long bow, but now BMW has come up with its own version of a performance car unplugged in the Z4 M Roadster. Slotting the M3's delicious 252kW, 3.2-litre six into the body of a Z4 might not be all that a surprising move; what is perhaps more unexpected is that very few of the electronic marvels released last year in the M5 sedan and M6 super-coupe have come with the M badge.

Count them: there's no SMG clutchless manual, no launch control system, no power-boosting buttons, no heads up speedo display, multifunctional traction and stability systems or active steering. In fact, with the Z4 M, what you expect is what you get: a harder, faster and grippier version of the Z4 roadster. Given that the Z4 is a pretty serious driving device in itself, that can be no bad thing.

While it's true the Z4M could be seen as a BMW parts-bin special -- much of what makes it tick has been lifted straight from the current E46 M3, with which it shares major platform components -- it's also an answer to the likes of Porsche, with its Boxster S, and Mercedes' SLK 55 AMG. Neither is the Z4 M unprecedented, for BMW had the Z3 MRoadster (and MCoupe) back in the 1990s.

The Z4 M Roadster goes on sale in Australia in April, costing $129,500. It will be followed a few months later by the Z4 M Coupe, which first showed itself as a concept car at the Frankfurt motor show only last September.

FEATURES
The M version of the Z4 comes along at the same time as a general facelift to the entire Z4 range. In typical BMW fashion the styling upgrade is fairly subtle: new bumpers and grille, different tail lights and front indicators, plus new rims, interior trim and instrument cluster. But "subtle" is, of course, a relative term when it comes to this car's existing long bonnet, flame-surfaced flanks and humpy-tailed boot lid.

More to the point, the Z4 now gets the new six-cylinder engines out of the new E90 3 Series. That means a 195kW 3.0-litre in-line six goes into what becomes the Z4 3.0si, and the 160kW 2.5-litre six is fitted to the Z4 2.5Si.

The M Roadster has its own look, with an even deeper front airdam and a black grille, fat 18-inch wheels and quad exhaust pipes exiting the rear bumper. It might not sound like much, but the impression is much more butch, with a squat menace missing from the standard car. It looks a little awkward and bubble-topped with the roof on, but flip it back (a motorised process that takes just 10sec) and the classic roadster shape is complete.

Inside there are sports seats, a fatter steering wheel with thumb grips, a bespoke gearknob and more leather padding on the dashboard to hide the peculiar angularity of the Z4's fascia. The tachometer has an illuminated redline, that decreases in breadth as the engine gain temperature after start-up

MECHANICALAnd what an engine it is. Despite being rumoured for replacement by a V8 in the next M3, and overshadowed by the (very) recent announcement of a new twin-turbo six, the classic 3.2-litre M-powerplant is a difficult act to follow. It produces 252kW of power at 7900rpm (just 100rpm below its rev limit) and 365Nm of torque at a highish 4900rpm.

Because the Z4 M is about 50kg lighter than an M3, performance is a bit brisker with 0-100km/h coming up in a claimed 5.0sec. That, by the way, compares with 4.9sec claimed by Mercedes for the SLK 55, and 5.5 for the Boxster S. But who's counting?

The M Roadster makes do with a conventional six-speed manual and no sign of SMG sequential. One of the reasons given for SMG's non-appearance is that the Z4 M had a short development life and is something of a niche model, so the decision to adopt just the one drivetrain was taken. But the M3's six-speed SMG is also seen as old-tech, and the M5's more sophisticated seven-speed wouldn't fit the Z4 floorpan. Either way, it's a boon for those who prefer DIY shifting and a let-down for anyone -- and it's presumed they exist --- who might prefer this car with some sort of auto.

Apart from DSC stability control, which can be flicked off at the touch of a button, and a Sport function to sharpen throttle response, that's about it on the driver's aids front. There are mechanical refinements, however, such as hydraulic power steering replacing the Z4's electronic assistance for better feedback and precision, and the variable M diff lock is fitted to make the most of available traction.

COMFORT
Just because BMW has unplugged the gee-whiz gadgetry of its latest offerings, doesn't mean the Z4 is short on luxury gear. It gets power-operated leather seats with warmers, the full-house version of BMW's satellite navigation, cruise control operated via a multi-function steering wheel and not a sign of any I-Drive nonsense to control minor (or major) functions.

Obviously enough, this is a two-seater so practicality is perhaps not a priority, although buyers can look towards the M3 (or M3 convertible even) if they want a back seat. The Z4 does offer a reasonably big boot, although no spare wheel but just a can of crack-filler and a pump.

Storage space in the cabin is more of a worry, with tiny door pockets and centre console space for a mobile phone behind the driver's elbow, but that's about it. There is a bin behind and between the two seats, but it is virtually inaccessible while driving.

But the seats are supportive, the driving position eminently adjustable including the ability to go extremely low. The roof operation might lack the wizardry of a folding hardtop, but there's virtually no waiting while it folds neatly into place without need for a cover.

SAFETY
The M Roadster shares the Z4's body structure with no extra strengthening -- a testament to the stiffness of the basic car. BMW claims exceptional rigidity and crashworthiness together with low overall weight, and although we can't verify the company's crash testing, there's virtually no body shake or flexing to indicate this is a 3-series platform with a missing roof.

Big brakes (345mm front, 328mm rear) are taken from the M3 CSL and backed by the latest ABS hardware. There's stability control, but interestingly, traction control is handled mechanically by the locking diff. Roll-over protection is provided by fixed hoops behind the headrests and there are front and side airbags but no curtain airbags.

COMPETITORSWe've already mentioned the Boxster S, which weighs in at $132,500 and offers less horsepower than the Z4 M, but is also more specifically-built as a sportscar with its rear mid-engined layout instead of a production car base.

The SLK 55 AMG is far more expensive at $163,400, but might well attract a different kind of customer with its big 5.4-litre V8, folding hardtop roof and auto-only transmission.

Apart from those two, there are very few hi-po two-seaters in the same ball-park. It's another $70,000 stretch to something like a Maserati Spyder, but it might be worth looking down the price scale instead of up.

BMW's own Z4 3.0si now has 195kW, and a claimed 0-100km/h time of just 5.7sec (6.0 for the auto) which isn't exactly slow for a $90,000-odd car. Then there's the Honda S2000 which offers a rip-snorter of an engine for $72,590. And this might sound silly, but you won't sample too many better drives than a Mazda MX-5 for the princely sum of only $41,860.

ON THE ROADHorsepower addicts are going to love this car. That glorious engine is immediately recognisable for its rising sense of urgency towards the 8000rpm redline, but also for the spread of torque that gives a surprising flexibility for its capacity. It might not pull hard from low revs like a V8, but neither is it left gasping if asked to overtake in higher gears.

The 3.2-litre six has the familiar M3 zing to the exhaust note, with the added benefit in the Z4 of no steel roof to muffle the sound. Without the complexities of SMG, and the vaguely disconcerting feeling of a computer-operated clutch, it hooks up in the lower gears and pulls hard in the higher ones.

If the move to hydraulic assistance was for improved feedback, then on the whole it's been successful. The Z4 M's steering is heavy at low speeds and a little wooden perhaps but there's good communication and no kickback.

Traction is complete on dry roads, thanks to the variably locking diff, and also a standard 18-inch wheel package with 255/40 rubber at the rear. Okay, the driver can pop a squeal of wheelspin on take-off, and a squeak for the first-second change but the balance of engine power to grip is pretty well perfect.

Not surprisingly, the ride is quite stiff and likely to be a whole lot more jiggly on rougher Australian roads, but we'd hazard a guess that BMW's uncanny knack of selecting damper rates might mean an acceptable degree of compliance. Certainly, the smoother Spanish roads where CarPoint sampled the Z4M on its international launch and odd pot-hole left the Z4 M unfazed and, as mentioned, the body is largely free of any looseness brought on by a lack of roof.

The launch took in not only Andalusia's winding mountain passes strewn with van-driving farmers, but also the Jerez circuit. There the uber-Z4 could be let loose, showing a degree of understeer on turn-in but more importantly, the adjustability to head into a turn with the rear tyres loaded and steer out on the throttle with the diff eking and holding the last whiff of available traction.

Although the brakes might be big, after a few laps of hard work on the circuit they began to fade quite noticeably, and stopping distances lengthened. That's not something likely to happen on the road (and didn't) but worth mentioning all the same.

What's more important is that the Z4 M is a couple of different things, both good. It's a sportscar with a great deal of togetherness, working with the driver, telegraphing its intentions and, above all, providing plenty of fun. But it's also a muscle car, endowed with great gobs of acceleration and unlikely to be beaten by many cars in a straight line.

Why would you buy one over an M3? That's a sticky question, and probably dictated more by fashion than anything else. But the Z4 M Roadster also has a raw exuberance that is gradually being refined out of BMW's M cars in favour of razor sharp efficiency. And that has its own great appeal in an unplugged kind of way.