Opportunity Missed

As BMW prepares to launch the MegaCity, we remember the rather similar Z13, the urban transportation prototype built two decades earlier by BMW Technik.

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February 24, 2011

As an in-house think tank charged with exploring ideas for innovative transportation, BMW Technik has been building attention-getting concept cars since 1985. Just two years after Technik’s founding, the first of those cars, the Z1—designated Z for Zukunft or future—wowed audiences at the 1985 Frankfurt auto show, setting the stage for a series of fascinating concepts to follow.

Only a few were presented to the public, but the Z13 unveiled at the 1993 Geneva Salon turned out to be one of the star exhibits. As audiences pored over its three-seat layout, compact dimensions and mobile communications tools, its creator Robert Powell found himself center stage, as well.

As Powell explains, the idea for the Z13 began germinating in 1974.

“One of my degree projects at the Royal College of Art in London was a single-seat car with a rear- mounted motorbike engine,” he says. “It was a very primitive design, but I liked it then!”

By the time the Z13 made its debut in Geneva, Powell had been working at BMW Technik GmbH for nearly three years, having been recruited to BMW’s forward-technology department from Porsche. That meant exchanging a 911 for a 5 Series and making a 155-mile commute each weekend from Munich back to his home in Stuttgart.

“The more I drove the 5 Series alone,” Powell says, “the more I began to consider the idea of a small, fast, safe, compact and lightweight intercity traveler optimized for one person with sat-nav, air conditioning, a perfect sound system and so on.”

Submarining at BMW Technik

Powell’s thoughts had precedent in a number of discussion papers co-authored by Dr. Volker Schindler in the late 1980s, just prior to Powell’ s arrival at BMW Technik. Schindler’s studies covered a gamut of topics including alternative drive systems, future energy supplies, the environmental impacts of emissions (acid rain, for example) and arguments for a “lean luxury machine” in the direction of a “personal car with maximum driving pleasure, comfort and safety.”

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Much of that, Powell says, became the background of the Z13 and to a lesser extent the Z11/E1 electric car of 1991 and the C1 scooter of 2000.

As the Z13 concept was being developed, Schindler’s ideas had an enthusiastic sup- porter in Dr. Klaus Faust, then head of BMW Technik. (Faust left in April 1992 to head up BMW AG’s chassis department, replaced first by Dr. Henning Wallentowitz and in 1994 by Dr. Mario Theissen.) Despite Faust’s enthusiasm, the Z13 idea was referred to by both Klaus Kapitza, BMW Technik’s head of design, and Powell as a “submarine”—i.e. unofficial—project.

For much of 1990, Powell and a small team worked out the details of “Projekt Z1- 3,” so named to suggest a variation on the Z1 roadster. When Powell presented their findings, director Faust loved the concept but was concerned about the legality of the central driving position. Still, the meeting resulted in the allocation of a small budget to Projekt Z1-3 that would enable the team to build a full-sized seating buck. Z1-3 would have to remain a part-time project, however, as Technik was concentrating its resources— including Powell’s manpower—on the electric car that became the E1, known within Technik as Z11.

In line with Faust’s reservations, the Z13’s most innovative aspect was indeed its seating arrangement, which positioned the driver in the center of the vehicle.

“A central seating position has many advantages and some disadvantages,” Powell explains, “but with it you can create a completely different centerline profile and more of a one-box shape, which I wanted. I used the centerline of the front wheels as the position of the pedals, which meant that the driver had at least 600mm (23.6 inches) of empty crash structure, which was unrivalled in any BMW at the time.”

Once the driver’s position had been determined, it became logical to place a small(ish) passenger seat to either side and behind it. To ease passenger ingress and egress, the size of the portal was increased by incorporating the sill and part of the roof’s perimeter into the door itself.

The rest of the design almost sorted itself out from there, Powell says. To add dramatic effect and give a feeling of openness to the interior, Powell continued the large wind- screen onto the roof, but the prototype omitted the glass door panels of his original concept sketches. The roof featured a slight depression towards the rear incorporating a small spoiler between subtle buttresses. The low-drag front had a cute button nose with BMW’s traditional double-kidney grille, while the rear featured sexy “hips” that seem to have found their echo years later on the Volvo C30.

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A prototype progresses

Work on the seating buck had “officially” begun on July 27, 1990, when Klaus Eberlein started its construction based on Powell’s drawings. By mid-November, Faust told Powell that he wanted Z1-3 to become Technik’s next official project. Soon after- wards, Z1-3 became known as Z13, losing its hyphen as it took its place in the sequence of BMW Technik concept cars.

A year later, the team presented its work to Dr. Wolfgang Reitzle, then BMW’s board member for research and development. Reitzle proved receptive, and further funds were allocated for the engineering support needed for Z13 to progress to the full-scale clay model stage that began in January 1992.

In May of that year, Powell and his team presented their work to not just Reitzle but also BMW chairman Eberhard von Kuenheim, showing both board members the full seating buck and the 1:1 exterior clay model that had been optimized in BMW Technik’s wind tunnel.

“Reitzle actually took over and did the presentation, as he was so involved in the project and loved it, ” Powell says. “Von Kuenheim, too, was impressed. From this point, the complete board was informed, a budget to build a running car was approved and space was booked for Geneva for its public presentation.”

Unusually, the project leadership consisted of Powell plus engineers Klaus Gersmann for packaging and Paul Gilke—the latter a “perfectionist,” according to Powell—to coordinate the meetings, write the protocols and source the new technologies that were to be an integral part of the Z13’s specifications, items like the satellite navigation system, Harman-Kardon sound system and space frame technology.

With respect to the latter, Powell had initially wanted to build the Z13 with a carbon fiber monocoque and aluminum subframes front and rear, but the project adopted the spaceframe technology developed a few years earlier for the Z11/E1 electric car, here mated with hand-beaten aluminum bodywork.

Powell had originally sketched the Z13 to be powered by a small, four-cylinder water- cooled Boxer (i.e. horizontally opposed) engine, but the prototype ended up being powered by the A34 inline four-cylinder engine sourced from the K1100 motorcycle.

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As fitted to the K1100, the A34 put out 100 hp at 7,500 rpm and 77.5 lb-ft at 5,500 rpm; the engine delivered from BMW’s Berlin-Spandau plant for use in the Z13 was modified to produce less power but more torque at lower engine speeds. In the Z13, it was mated to a Continuously Variable Transmission (CVT) purchased from Ford, which was then using it in various small cars sold in Europe.

This engine-transmission combination was selected for its refinement as well as its power. Crucially, the chain-driven DOHC engine was also relatively light: Its major castings were aluminum alloy, and its pistons ran in linerless silicone-etched cylinders with a bore and stroke of 70.5 × 70mm for a capacity of 1,093cc.

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.”

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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.

“I drove this prototype regularly for some time after it had been completed and found it somewhat nerve-racking driving a hand- built car worth several million Deutschmarks around on the crowded roads of Munich,” remembers Powell.

As mentioned earlier, both cars positioned the driver front and center, with seating for two passengers immediately behind and to either side. As in the 850i coupe, BMW’s top model, the driver’s seat in the Z13 had an integrated seat belt system and an airbag in the steering wheel hub. The front seat could accommodate even a large adult in comfort, though the two passengers needed to be fit and slim to slide into their seats.

The driver experienced a panoramic view to the outside, and all instruments and controls were easy to reach and use. Directly in front of the driver on the gently curved dashboard, a hooded binnacle contained typically large BMW dials: a speedometer graduated to 240 km/h, a tachometer that redlined at 6,000 rpm, a fuel gauge to the left and a temperature gauge to the right. To the left (almost in front of the passenger) sat a screen for the sat-nav system and a mobile telephone; on the right was the rotary dial that controlled CVT operation, the electromechanical parking brake and the high-end sound system. Space for soft luggage was available over the engine and behind the driver’s seat, and it could be extended by folding down one or both passenger seats.

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The Z13 project continued into 1994, with further clay models built and different technical concepts explored. The BMW grapevine said the car was destined for production, most likely with its space frame clad in recycled plastic a lá the Z1.

And why shouldn’t it go into production? Von Kuenheim and Reitzle loved it, the media fawned over it and the public assumed that the car had been shown at Geneva as a prelude to its arrival in dealer showrooms.

Car, interrupted

Just as the Z13 project was moving into a critical phase, however, BMW announced its purchase of Britain’s MG-Rover corporation, which included Mini as well as a host of long-forgotten marques like Wolseley and Morris.

Buying the “English Patient,” as the subsidiary soon became known, gave BMW a ready-made city car in the Mini. The Z13 was no longer needed.

Although the MINI built under BMW’s ownership went on to become the world’s leading premium compact car, the Z13 would have represented a major step forward had it gone into production. It was unlike anything on the market in 1993, and the industry has taken nearly two decades to match it. The 2005 Citroen C1 and Peugeot 107 as well as the 2008 Toyota iQ are virtual Z13 clones, while the 2009 Nissan Pixo/Suzuki Alto show its influence, as well. BMW itself took even longer to revive the concept, adding a model beneath the MINI only with the MegaCity due in 2013.

Even though his project never went into production, Powell remained with BMW’s design department until the end of 2009, when he established his own design company near Munich.

“I am still really proud of Z13,” Powell says. “It still looks good 17 years later, and it’s a pity that photographs do not really capture the car ’s dynamics. The press kept referring to it as a ‘city car,’ but it was more than that. Z13 was meant to be driven!”

Also from Issue 98

  • Driving the new 650i Cabrio in S Africa
  • 740Li vs. 750Li xDrive
  • Dinan's 408-hp/440 lb-ft 335i
  • The history of the legendary 328 Bügelfalte
  • A thoroughly hot-rodded E24 635CSi
  • A lovely Golf Yellow 2002 tii restoration
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