BMW Just 4/2


If you're running a car company, you've got to find ways of keeping your best designers, engineers, and other employees focused on where the car market might be.

Maybe not today, or tomorrow, but off in the future. It's an essential exercise in order to stay in step with how the car market may change.

Honda, for instance, would cycle some engineers through its race programs in order for them to become better engineers. General Motors, Ford, and others all have secret "skunkworks" for cobbling together new prototypes.

For more than 25 years, BMW's experimental arm has been its (Forschung und) Technik GmbH research division.

Tasked with creating new types of vehicles and bringing them to concept or prototype form, one of the division's very first projects was a small roadster with retractible doors—which entered production as the Z1.


From electric city cars (E1) to so-called off-road roadsters (Z18), they ranged from feasible to whimsical—but at least BMW made the effort to ensure they were running, driving prototypes.

Just 4/2 was, as you can guess, a design based on the idea of driving pleasure. German designer Michael Powell was to head up the project, known internally as the Z21. 

A former Porsche designer, he was responsible for a number of things, from the interior of the 959 to the world famous Rothmans livery as-seen on the Dakar 959 and 962 race cars.

Moving to BMW's Technik division, he was responsible for the earlier Z13 concept: a city car with a mid-engined design, 1+2 seating (like the McLaren F1), and power provided by the firm's K1100 1,000cc motorcycle motor.


For the Just 4/2, things would be much more simple: rear-mounted BMW K-Series motorcycle engine with 100 horsepower,  weight of 535 kg (1180 lbs.), and open bodywork, it arrived two years before the first student sketches that would eventually become the Ariel Atom.

Both are very similar designs, with the Just 4/2 taking less of a hardcore track day focus—it's more similar in temperament to the just-released Polaris Slingshot 3-wheeler.

For the record, this is one of my all-time favourite press photos!

For the record, this is one of my all-time favourite press photos!

0-100 km/h (0-62 mph) for the Just 4/2 was dispatched in around 6 seconds, with a top speed of 195 km/h (120 mph)—quick enough.

Powell has a design consultancy, and as part of his website has (thankfully) provided many details on the car's development. One of my favourite anecdotes is how the managing director of the ZT division (the internal code for BMW Technik) at the time was Dr. Mario Theissen, who would later become the boss of BMW Motorsport. (And the team principal of BMW Sauber!)


A link to much more detailed design information is available in the sources, but for the most part you can work out the design brief: a frame of aluminum extrusions, front and rear suspension points mounted to it (with the springs elegantly perched under the same swath of frame); carbon fibre body panels, waterproof interior, simple dashboard… 


…the car was made to drive. That doesn't mean there weren't a few concept car tricks: pedals to lower the scissor doors, matching clothing line, and detachable carbon fibre trunk.

Of course, Just 4/2 never entered production, despite the Technik team's best efforts in trying to bring it to production. Its first and last major public auto show appearance was the 1995 Tokyo Motor Show—where Masako, Crown Princess of Japan* sat in the car and said:

"I think you will need an umbrella with this car." 

Sources / Recommended reading

* She's essentially the daughter in-law to the Emperor of Japan