The car industry falls prey to collective hysteria occasionally, never more so than when it came to the strange cult of the retractable hard-top. With a decade of hindsight since this regrettable trend peaked it's hard to think of a single car that was made better by the need to carry a complex, heavy and likely-to-fail folding roof mechanism, but easy to create a list of those that were made worse. A list with the last generation BMW Z4 right at the top, its name heavily ringed in red.
The first Z4, the 2003 one, was amusingly raw and offered simple thrills, qualities reflected in the minimalist fabric hood worn in roadster guise. But its 2009 successor, the E89, was permanently compromised by the decision to launch it wearing fashionable headgear. The line from marketing was that the Z4's power operated hardtop meant it was both a roadster and a coupe at the same time. Technically this was correct, but only in the sense that it was a lardy, ungainly roadster lugging necessary mass far too high - or a strange looking coupe with wind noise issues and a frequently obvious lack of torsional rigidity. When the E89 quietly died last year, most people didn't even notice that it had gone.
The lesson has been learned; the new Z4 returns to a fabric roof and - on first impressions - is a much better car for it. Indeed on the basis of our drive of a prototype version nearly a year ahead of UK sales starting, the Z4 also looks set to become a proper sports car again.
First, let's get the question of the Z4's parentage out of the way. The internet has been frothing about the exact mixture of the partnership between Toyota and BMW to build the Z4 and what, until proved wrong, I'm going to carry on calling the new Supra. Some reckoned it would be a 50:50 effort, others were even hoping that BMW was basically going to stick its badge onto a full-engineered Toyota with the modern-day equivalent of a 2JZ engine in it. But the reality is that the engineering is almost all Munich, with both cars set to sit on the same BMW-designed platform, being assembled together by contract spanner house Magna Steya in Austria. The big difference is up top, the Z4 being a roadster and the Nu-Supra a coupe.
BMW will be launching the Z4 with a pared-back engine range. The Z30i will use a four-cylinder motor producing around 250hp, while the M40i version has the twin-turbo straight-six that's already offered in other 40-badged cars. Outside Europe this has been given a power boost to 382hp, but EU spec cars will come with a petrol particulate filter - yes, that's a thing now - limiting output to the 335hp of the M240i. All versions will share the same 369lb ft peak torque output, with drive dispatched exclusively through the rear axle and an eight-speed ZF autobox, the Z40i also getting an electronically controlled limited-slip differential as standard. A manual would have been nice, but BMW admits there isn't enough demand in any of the likely big Z4 markets to justify the development cost.
Sorry about the dazzle disguise; BMW was happy to show me what the finished car will look like, but we weren't allowed to take any pictures of it. The cars I got to drive on the Miramas test track in Provence, and some of the local roads surrounding it, were all hard-beaten development mules designed to demonstrate chassis attributes rather that fit and finish. Having seen the (visually) finished version I can report that it has a huge clamshell front bonnet, the twin headlight elements are now stacked on top of each other and that the front overhang is as ungainly as it looks on the prototypes; apparently it is mostly the result of the need to meet various pedestrian impact standards without a significant increase in the height of the car. Tellingly, although this Z4 is 82mm longer than the last one, its 2470mm wheelbase is actually 26mm shorter.
BMW sends me out to learn the Miramas handling track in a BMW M2; a brave call given the risk that the less-focussed Z4 might seem lacking by comparison. The coupe relishes the circuit's mix of low and medium-speed corners, stability control struggling - and sometimes failing - to maintain rear axle discipline. A not-quite-M version of the Z4 is going to feel pretty tame by comparison, surely?
First impressions are that yes, it does. I've got an engineer riding shotgun and instructions to set off in the car's softer Comfort mode, meaning the gentlest settings for the active dampers, powertrain and electrically assisted steering. As such, the Z4 feels predictably comfortable, riding out crests and occasional chunks of kerb with respectable suppleness but with noticeable understeer behind the initially crisp front-end responses. The engine and gearbox work well together, left in Drive the ZF has a happy knack of being in the right gear at the right time, and even under lower-intensity use the engine's purposeful rasp sounds better than the Porsche 718.
Yet it soon transpires that this has been a subtle ruse to demonstrate the breadth of the Z4's ability. Once the dynamic mode is switched to Sport the Z4 practically chugs a can of spinach, the M40i's standard active dampers firming up noticeably, the steering gaining heft without losing feel and the throttle response instantly shedding the elasticity of the gentler setting. The really clever bit is the electronically controlled LSD, which doesn't play much of an obvious role in Comfort, but which now starts to intervene hard as it wages a personal war against front-end push. On the way into corners the diff stays open, with torque biasing through the brakes helping to get it turned, but once on the throttle the differential can be felt locking aggressively to help deliver traction and - as the engineers put it - over-rotate the car.
In longer turns the Z4 hunkers down to an exciting-feeling edge-of-oversteer stance. In truth, it's not quite as heroic as it first feels, with experimentation proving that even stamping the accelerator doesn't create the sort of lurid powerslide the car seems to be threatening. Turning the stability control off does turn it properly lairy, although most will struggle to get it as close to the limit as nanny manages.
Other stuff is good, too. Despite being a torque converter the gearbox changes impressively fast under manual control, although the plastic steering wheel paddles feel insubstantial and the wheel itself follows BMW's recent trend of making rims needlessly thick. (Here's an idea: copy the almost unimproveable wheel from an E46 M3.) The brake pedal has good resistance and feel, with the standard iron discs doing a decent enough job on track to more than justify the decision not to offer carbon discs as an option and the Michelin Pilot Super Sport tyres withstood hard use with a similar lack of complaint. You'd be unlikely to buy a Z4 for regular circuit work, but it feels like it can certainly cope with a proper pasting.
Time for a brief turn outside the confines of the test track. Some of Provence's quieter roads give a more realistic test of how new Z4 will cope with a typical duty cycle. At normal speeds the clever differential is less obvious, but the engine's strong across-the-board responses and the gearbox's refined manners make it effortlessly quick without becoming dull. The motor revs happily to 6500rpm, and will touch the 7000rpm limiter in Sport and Sport Plus mode; there is a sound symposer in the cabin but all the noise heard with the roof down is produced naturally.
Rougher surfaces also give the chance to put the clever damping to the test but also to test the core strength of the Z4's structure. BMW's engineering team say it is around 20 percent more torsionally rigid than the last Z4, and even corrugated surfaces didn't produce any sensation of scuttle shake. The adaptive dampers don't feel sloppy in Comfort, nor do they get excessively harsh in Sport. Refinement with the roof up is impressive as well, although with the roof down there's a fair bit of buffeting at the sort of higher cruising speeds the car encourages.
The signs then are encouraging. The previous BMW Z4 felt like a bit of a half-hearted effort; many people wouldn't have been surprised if it had been the manufacturer's last roadster. But the Toyota partnership has given both the budget and the engineering effort to do a considerably more proper job. We'll have to wait to see how the finished version feels, and to see how it copes with the unique challenge of the UK, so don't cancel that 718 Boxster quite yet. But, on first impressions, this is a welcome return to form.
SPECIFICATION - BMW Z4 M40i (prototype)
Engine: 2,998cc, straight six, twin turbocharged
Transmission: 8-speed auto, rear-wheel drive
Power (hp): 335@5,500rpm
Torque (lb ft): 369@1520rpm
0-62mph: 4.4sec (provisional)
Top speed: 155mph
Weight: 1,500kg (DIN, without driver)
Price new: TBC
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