The complete engine and transmission assembly was mounted in the rear mid-engine position, just ahead of the rear axle. The plastic molded fuel tank sat just in front of it, under the seats, where it would be safe in a collision. This disposition also gave better weight distribution and thus handling.
All the Z13’s other components—suspension, steering and braking systems—were sourced from BMW’s regular suppliers and modified where necessary. As was typical of a BMW in that era, the front suspension consisted of MacPherson struts and coil springs while the rear used semi-trailing arms with mini-block coil springs. Braking was by four-wheel discs with solid rotors and ABS, the steering by rack and pinion.
The construction of the Z13 show car was contracted to the Italian carrozzeria of Stola in Turin, which could build it far more economically than BMW Technik could do in-house. Powell and Gersmann found themselves living in Turin for some months, while other BMW engineers flew back and forth as required. Fritz Schub and his team from the prototype workshop, for instance, spent about two weeks in Turin installing the drivetrain, suspension, etc. near the project’s completion.
“We were building a fully drivable prototype, and the demands of that go way beyond the requirements for a normal show car,” Powell explains. “Besides, BMW sets extremely high standards for drivable show cars. We were building Z13 to production car standards.”
Working at Stola was a new experience for Powell, in particular. “I will never forget watching those incredibly modest craftsmen hammering the aluminum panels by hand,” he says. “The rear fender with its large air intake was one piece, and I found it most humbling to arrive at the factory and have these craftsmen await my approval or acknowledgement of their work.”
Best of all, they worked quickly. “Italians are renowned for their inability to follow the clock, but somehow it all was finished on time!” Powell exclaims.
At the beginning of March 1993, the blue Z13 made its debut at Geneva. It would make the motor show rounds for the rest of the year, accompanied most of the time by Powell.
Up to date and fully drivable
Shortly thereafter, a second Z13 was built. Though painted red instead of blue, it was otherwise the same as the original Z13 prototype, at least superficially. Underneath, however, it differed significantly in its construction details, having been built to the specifications envisioned by Powell at the outset. Interestingly, the red car had more interior room as a result of the change in construction that saw it employ an aluminum profile frame (made by Hydro Aluminum) clad with aluminum body panels.
Underneath, the CVT gearbox was replaced by a five-speed manual transmission, and the engine was upgraded to the 1,171cc A36 four sourced from the K1200 motorcycle. As in the first Z13, the engine lay on its side and the transmission was transversely mounted at the rear. The red car had a top speed of 112 mph, making it capable of safe travel on both city street and autobahn.