Little red roadster
Carefully leaked in 1986, and officially announced at Frankfurt last year, BMW’s little Z1 roadster is now on the road. The high-tech rear-wheel-drive two-seater was given an official Press launch in Italy a few weeks ago to universal acclaim. But, due partly to its unusual construction and partly to its limited market, it will remain rare and expensive, even on home ground.
Z1 sales will be an insignificant blip on the BMW’s sales graph over the next few years. But it is a vital product for the company nevertheless; its value as a show-car is necessarily short-lived, but its appearance has highlighted BMW’s latest offshoot, BMW Technik. An independent “think-tank” of some 100 styling and technical experts, BMW Technik has a brief to investigate future materials and techniques without worrying about production constraints. Its main objective in this, its first project, was to study ways of shortening the gestation period for new models. That the project turned into a car at all, and a sports-car in particular, is, claims BMW, due to the collective enthusiasm of the team. And that the car was “sold” to the BMW board and is now in production shows the extra flexibility which the new department offers.
As a vehicle for new technologies, the Z1 excels; it has an all-plastic body, novel rear suspension, and those innovative doors which can be left open while in motion. Even the German TUV has agreed that this is safe, and BMW is confident that other countries will take the same view. The slim doors drop down into deep side-sills which give the chassis immense rigidity and safety from side impacts.
Yet there has been no compromise over comfort and practicality; careful attention to aerodynamics has resulted in minimal draughts in the cockpit, the smooth spoiler-free styling conceals impact-absorbing bumpers beneath highly flexible panels, the screen surround forms a roll-bar and there is a small boot in the stubby tail. Power comes from the well-proven 170 bhp straight six engine and five-speed box from the 325i, but set well back in the galvanised steel chassis.and solidly connected to the differential through a thick alloy tube. This “spine” has only three body mounts (two front, one rear), and gives the stubby car a 49:51 front/rear weight-balance. The pressed steel parts which make up the car’s frame are further strengthened by bonding in a composite floorpan, and even the galvanising process is claimed to add rigidity.
All the running gear is attached to this frame, so that the skin is completely stress-free. A new paint process was required to handle the three different materials used for the body; injection-moulded high-impact plastics for the sides and wings, elastic material for the “bumpers”, and foam-cored fibre composites for bonnet, boot and roof cover. All these panels can be removed in 30 minutes. These methods, says BMW, save some 100kg over conventional construction to achieve the same rigidity. At the front, a wide-track variation on the 3-series strut is employed, but the rear wheels are located by a new and very accurate system known as the “Z axle”. Two lateral arms guide the wheel vertically, while a massive trailing link curves round the tyre from a pivot in line with the hub. Camber changes and bumpsteer are eliminated, but there is a degree of passive steering; toe-out is introduced to give crisper turn-in, changing to toe-in as lateral forces rise, minimising the risk of throttle-off oversteer. Eccentric bushes allow for fine adjustment should anyone want to take to the track.
BMW claims that the Z1 can generate up to 1G laterally on its 16in 225/45 tyres, and certainly several rapid ascents of a mountain pass proved that the little car has exceptional roadholding. What is more, BMW has achieved a superb degree of high-speed damping without making the car hard over slower abrasions. It deals firmly with sudden brows or mid-corner bumps, keeping the wheels in touch with the ground and generally feeling as lively as a go-kart, but rather more comfortable.
Though the 3-series power steering is not especially fast, the sheer sharpness of the chassis gives the Z1 a delightful feeling of agility; it is completely stable under rapid cornering, and if the bend proves to be sharper than expected, a further twitch of the wheel instantly gives a tighter turn. Stylish seats keep the crew anchored, and the cabin layout is well up to BMW standards, with plain round dials under a motorcycle-style cowl. There is only one flaw inside — a complete lack of storage, although a panel can be removed to give access to the boot and even to carry skis. Stopping power comes from the 325i but with larger rear discs, and ABS is standard.
Driving with the doors down will feel novel to anyone who has not driven a pre-war sports-car, but is fairly windy at 40-plus mph; better to flick the handle and watch the lightweight panel glide up (it can be done manually should motor or battery fail). Buffeting from behind, the perennial sports car bugbear, has been virtually eliminated, helped by free-standing mirrors on the A-pillars, and rear axle lift substantially reduced by channelling air up under the tail around a wing-shaped exhaust silencer. A separate motor on the chassis operates the window through an ingenious L-shaped link.
Like the 3-series convertible, the hood is concealed by a smooth cover when down, and it flips up with one hand. There are no hooks or poppers— when tensioned, it presses down on the cover behind the seats and locks into the screen rail. The rail itself is unusual in standing proud of the top of the screen; this increases its strength in a roll-over, and makes a useful grab-handle for getting in and out. Top up, visibility is still good through the glass rear light, and wind noises are low.
In its design and execution, the little Z1 is a gem: its exciting styling is likely to form a keynote for other studios; its driving qualities are superb; its unique doors offer a novel driving experience. For its makers it has proved several new ideas, not least that the new Technik department will be a real asset.
But its very success is likely to be a problem. Such a vehicle cannot be adapted to automated assembly; instead it will be hand-built at a rate of about ten a day in the small area in the main BMW plant vacated by the old pilot line, now removed to a new Research and Engineering Centre. Only some 1500 cars will be built in 1989, and yet orders already exceed 4000. If demand continues high, double-shift work might help, but BMW will wait and see, as it will for RHD and American versions.
Meanwhile, with its M3 success as a guide, BMW (GB) feels that it could be selling 100 cars a year or more in Britain, even in LHD and at a cost well over £30,000. But it will be interesting to see which of the four Z1-only colours sells here: bright red of course; metallic black and dark green also. But lemon yellow may prove to be a rarer sight. GC
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