As Rivolta was abandoning car building, German auto and motorcycle manufacturer BMW was undergoing financial difficulties. Its luxurious, expensive six- and eight-cylinder cars were beautiful machines but they were expensive and weren’t selling well enough to generate profit. Motorcycle sales were also soft. Faced with possible bankruptcy BMW had to do something, so to get into the affordable bottom end of the car market it bought the rights to Renzo Rivolta’s Isetta.

BMW replaced the Isetta’s two-stroke engine with a modified version used in one of its motorcycles, an air cooled 247 cc, 12-horsepower single-cylinder, four-stroke. A 295 cc, 13-horsepower engine would be added in 1956 for the export models named the Isetta 300. BMW also fitted a more conventional trailing arm and coil spring front suspension in place of the horizontal coils used by Rivolta.

The Isetta sold well enough that BMW could afford to expand the line with a four-passenger version in 1957. Called the 600, it had a flat-twin, 585 cc, 19.5-horsepower motorcycle engine. The 600 retained the front opening door, and added a right rear side door for access to the surprisingly roomy back seat. Transmission shifting was through a conventional four-on-the-floor lever.

Isettas were also built under licence in France, Brazil and England. Total production between 1955 and 1962 was almost 162,000 in four versions: bubble window, sliding window, and convertible, plus a rare pickup truck.

The Isetta’s performance was definitely not freeway friendly. Road & Track (2/’58) tested a 300 and recorded a top speed of approximately 80 km/h (50 mph) and 0–40 mph (64 km/h) acceleration in 20 seconds. Fuel economy was tremendous, however, being in the 60 to 75 mpg range.

The Isetta engine was started by a combination generator-starter unit called a “Dynastart”. Visibility was excellent, akin to a fishbowl, which was an important feature because large potholes would easily swallow the Isetta’s tiny 10-inch wheels. Parking, of course, was a breeze — simply nose into the curb and step out onto the sidewalk.

When the Isettas reached North America, their drivers could not be shy or retiring because the car attracted considerable attention. The most often heard enquiry was: Is this really a BMW? Many people apparently missed this short chapter in BMW history.

The two-passenger Isetta 300 and 600 helped BMW pull back from the brink of bankruptcy. It introduced a 700 model in 1960, a more conventional appearing car, although still powered by a rear-mounted, air-cooled twin. The big break came in 1962 with the launch of the conventional 1500 sedan, forerunner of the very successful 2002 model.