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The Top Gear car review:BMW Z1
For:Lovely chassis, super-sweet engine, those crazy doors
Against:Could be a little quicker. Looks inelegant from some angles
What is it?
This, the 1989-1991 BMW Z1, is the origin of the modern-day BMW small-roadster line that runs through the Z3 and three generations of Z4. Sadly, never again have they been this distinctive.
Oddly, the point for BMW was never specifically to build a roadster. It was to let its new Technik research skunkworks explore fresh ideas in engineering, as well as new development processes, and body construction for small-volume cars. The Z stood or Zukunft, or future.
While they were being encouraged to bring some fresh air into their engineering thinking, they went positively blue-sky with the doors. They came up with a deep-silled design for the structure. Lo and behold there was space for the shallow doors to retract downwards instead of hinging outwards. Pull the handle and the glass window drops into the door, while the door itself motors electrically right on down.
Yes, it’s possible to drive doors-down. TG remembers doing so in London back when the first one came to the UK. This was just before the MX-5, so a roadster was rare enough, let alone a mad-looking left-hand-drive one off which the doors had apparently fallen. Bystanders went nuts for it. Driving it again in 2018, the novelty is fully intact.
But this is about far more than the doors. The body is an innovative steel monocoque welded up from sheet steel then galvanised. The floor is a plastic sandwich, bonded in to give huge extra strength. Onto all that goes a plastics body. The sides and doors are thermoplastic, most of the rest GRP, all of them injection-moulded, with various foam cores and some bracketry moulded in. The panels bolt on.
Next party trick: the car drives perfectly well naked. You could change colour, according to BMW’s official history: “In theory, with a complete second set of outer panels it would have been possible to convert a Z1 from red to blue in the space of an hour using nothing more than a screwdriver.” It takes at least a day, say those who’ve been brave enough to try.
The Z1’s skin and shallow-angle windscreen made very low drag. The aero was carefully developed, with that underfloor killing nearly all lift and the transverse-mounted silencer acting as an underbody wing, the air departing above the bumper.
Most relevant of all to future BMWs was the rear suspension, a multi-link arrangement later to be known as the Z-axle, which made the E36 3 Series such a brilliant car, and gradually spread across the range.
Probably the biggest disappointment was the engine. Not its layout – a lovely BMW straight-six – but its power. This was the last days of the 12-valve, and even in 1988, 170bhp didn’t seem dramatic enough. Especially not given the awesome grip and handling. It could have taken far more.
The Z1 was designed by Harm Lagaay, later to become overlord of the pencils at Porsche, doing the Boxster and 996. The Z1’s engineering boss was Ulrich Bez, who’d come from Porsche where he developed the 993. Later he moved again to be overgaffer at Aston Martin. It was an aristocrat of a car with proper connections.