BMW built the Isetta "bubble-car" under licence from ISO of Italy, which was primarily the maker of motor-scooters and three-wheeler utilities. ISO introduced the Isetta in 1953 and also sold a licence for its production to Velam in France. ISO's owner, Count Renzo Rivolta, eventually spent the profits from these agreements on making the Euro-American ISO Rivolta and ISO Grifo supercars.
   The BMW Isetta 250 dispensed with ISO's two-stroke engine, using instead the four-stroke 247cc single-cylinder engine from the R25 motor cycle. From February 1956, there was a companion Isetta 300, with the more powerful 297cc engine from the R27 motor cycle. Other changes included smaller headlamp cowls after 1955 and a completely revised glass area with larger side windows from October 1956.
   The original ISO car, the BMW version and the Velam all had twin rear wheels, but a version of the Isetta 300 built under licence from BMW in Britain from 1958 actually had a single rear wheel, because three-wheelers attracted less purchase tax and their road fund licence was cheaper. Just 1750 three-wheelers were built.
   In the mid 1950's, the Isetta cost just 20% of the cheapest of the Baroque Angel 501 saloons.

   The 600 was a logical progression from the Isetta and must have seemed like a good idea at the time, but sales of just over 34,000 in two years never matched BMW's expectations. Part of the problem was the price - the 600 was only just cheaper than the entry-level VW Beetle. But it was also undeniable that buyers in the late 1950's wanted cars that looked like cars and were quickly losing interest in economy models which suggested that their owners might not have much money. Without the short-lived vogue for economy cars which followed the Suez crisis of 1956-57, the 600 might have flopped badly.
   Designed by Willy Black, the 600 was unashamedly intended as an enlarged Isetta with more power and a "proper" four-wheel configuration. Its front end was pretty much unchanged from the Isetta, but the wheelbase had been stretched to accommodate four seats and a conventional rear axle had been added. This introduced to BMW the semi-trailing arm independent suspension which would be seen on almost every new model for the next four decades.
   The extra size and weight demanded a more powerful engine than the Isetta's and so the 600 had yet another motor cycle powerplant - this time the 582cc twin from the recently defunct R67. Top speed was a not unreasonable 64mph.