8000 built between 1988 - 1991.

Launched in 1988 with a price tag of around 39,625 pounds, the aerodynamic BMW Z1 (the "Z" stood for "zunkuft" - German for "future") was a two-seat roadster with a top speed of 140 mph.
The Z1 featured unusual doors which instead of opening in a conventional manner, actually dropped down into the door sills.
Initial demand was so strong that BMW had 5,000 orders before production even began. A four wheel drive model was also designed but never produced. Only 8,000 Z1s were built and they were all LHD although we believe that a RHD conversion was possible. Production ceased in 1991 thus making this car a very desirable modern-day classic. (source: art of motoring).

The BMW Z1 is a two-seat roadster developed by BMW Technik GmbH and produced from July 1988 to June 1991. The Z1 featured unusual doors which, instead of opening outward or upward, dropped down into the door sills.
The first example of a Z1 was released by BMW to the press in 1986 and later officially presented at the 1987 Frankfurt Motor Show.
Initial demand was so fierce that BMW had 5,000 orders before production began. Unfortunately, demand dropped significantly around 1988 and BMW ended production in 1991.
There is speculation that this drop in demand was due to the introduction of the Mercedes-Benz SL (Brossaud, 1) and the early inflated demand from speculative investors. In 1988, however, BMW was quoted as saying that they had 35,000 orders for Z1s.
The BMW Z1 was designed over a three-year period by an in-house division of BMW Technik GmbH. The development of the Z1 is attributed to Dr. Ulrich Bez, not to forget the core of his team at BMW Technik GmbH (Alexander Pregl, Rudolf Muller, Lutz Janssen, Wolf-Henryk Menke, Dieter Schaffner, Klaus Faust, Sabine Zemelka and Stephan Stark). Control of the project was turned over to Dr. Klaus Faust when Bez left for Porsche in October, 1988.
BMW considered building an all-wheel drive model but this was later scrapped.
The BMW Z1 was used to develop and debut several technologies. Z1 designer Harm Lagaay mentioned that Z1 production helped generate patents for BMW's high-intensity discharge lamp, integrated roll-bar, door mechanism, and underbody tray.
Chassis.
The chassis was specially designed for the Z1 and features a number of innovative features: removable body panels, continuously zinc welded seams, a composite undertray, and the unusual dropped doors. Parts of the car (including the engine, gearbox, and front suspension) were borrowed from the BMW E30 325i, but the Z1 remains largely original.
The body was reportedly made from three (or five, depending on the source) different types of plastic and could be removed completely from the chassis. The side panels and doors are made of General Electric's XENOY thermoplastic. The hood, trunk, and roof cover are GRP components made by Seger+Hoffman AG. The car is painted in a special flexible lacquer finish developed jointly by AKZO Coatings and BMW Technik GmbH.
During the Z1s launch, BMW suggested that owners purchase an additional set of body panels and change the color of the car from time to time. The car could actually be driven with all of the panels completely removed, similar to the Pontiac Fiero. BMW noted that the body could be completely replaced in 40 minutes, although Z1 owners have reported that this may be optimistic.
The entire vehicle was designed with aerodynamics in mind. In specific, the entire undertray is completely flat and the muffler and rear valance were designed as integral aerodynamic components to decrease turbulence and rear lift. The front end reportedly induces a high-pressure zone just forward of the front wheels to increase front-wheel traction. The Z1 has a drag coefficient of 0.36 Cd with the top up or 0.43 Cd with it down.
Doors.
One of the most interesting features of the Z1 is its unusual doors. These doors retract vertically down into the car's body instead of swinging outward or upward. The inspiration for these doors came from more traditional roadsters which often feature removable metal or cloth doors. Because removable doors did not fit within BMW's design goals, the retractable doors were installed instead.
Because the body, with its' high sills offers crash protection independent of the doors, the vehicle may be legally and safely driven with the doors up or down. However, see discussion page.
The windows may be operated independently of the doors, although they do retract automatically if the door is lowered. Both the window and door are driven by electric motors through toothed rubber belts and may be moved manually in an emergency.
Driveline.
As mentioned above, both the engine (the BMW M20B25) and the five-speed manual gearbox (the Getrag 260/5) were sourced from the E30 325i. The 2.5 L (2494 cc) 12-valve SOHC engine sits tilted 20 degrees to the right to accommodate the low hoodline.
The engine produces 170 hp (127 kW) at 5800 rpm and 222 N·m (164 ft·lbf) of torque in its original form, although several tuners have programs for increasing the performance of the Z1 by either upgrading or replacing the engine. A common complaint is that the gearbox isn't well-matched to the engine or the car's sportiness.
Suspension.
The rear suspension, called the Z Axle, was specially designed for the Z1. It was one of the first BMWs to feature a multi-link design. The Z1 was outfitted with 15 in (381 mm) diameter by 7 in (178 mm) wide wheels on both the front and rear, shod with 205/55VR-15 tires.
Interior.
Although the unique doors are innovative, larger customers have commented that the high door sills make exits and entries difficult. Additionally, the interior is hand-assembled and may suffer rips and tears after years of use.
The instruments on the Z1 are styled like motorcycle gauges, and the tachometer on the Z1 has a red needle, whereas all other gauges have a white needle.
1990 BMW Z1. (source: BMW)
1990 BMW Z1 body panels. (source: BMW)
1990 BMW Z1. (source: BMW)
1988 BMW Z1. (source: BMW)
1988 BMW Z1. (source: BMW)