by Bill Vance
Bubble cars came onto the European auto scene in the 1950s in response to high gasoline prices, and the need for low cost weather-proof, personal transportation. Names like Messerschmitt, Heinkel, Goggombobil and Isetta began to appear on these tiny, usually three wheeled cars powered by air cooled engines. They were a step up from a motorcycle and sidecar, which is what many people were using for family transportation.
In 1952 a refrigerator manufacturer, Renzo Rivolta of Milan, Italy, entered the car business. His fridges carried the Iso brand name so he called his little vehicle the Isetta, literally “small Iso.”
The Isetta, introduced in 1953, set the whole bubble car trend in motion. The most striking feature of this egg-shaped, two passenger vehicle was the method of entry and exit. Perhaps Rivolta was influenced by his refrigerators when he designed it because the entire front of the car, including the windshield, was a door that swung out, bringing the universal-jointed steering column with it.
Occupants stepped aboard, turned around and sat down, and the driver pulled the steering wheel back to close the door. In the event of a frontal crash, passengers escaped through the sunroof.
The 1,194 mm (47 in.) front track was about normal for a small car of that era, but the mere 508 mm (20 in.) between the rear wheels was decidedly unusual. It did, however, eliminate the need for a differential; a chain transmitted the power from the engine to a large sprocket attached to the drive axle in the rear housing.
The Isetta was powered by a 236 cc two-stroke, two-cylinder air-cooled engine mounted just ahead of the right rear wheel, the location chosen to counterbalance the driver’s weight. The four-speed transmission was shifted by a lever with an “upside-down H” pattern, located to the left of the driver.
Rivolta built the Isetta until 1955, when he decided to stop, although he would return to car building in 1962 with vehicles at the other end of the spectrum: high powered sports cars called Iso Rivoltas.
As Rivolta was abandoning car building, the German auto and motorcycle manufacturer, BMW, was undergoing financial difficulties. Its luxurious, expensive six-and eight-cylinder cars weren’t selling well, and motorcycle sales were soft. Faced with possible bankruptcy BMW had to do something, so in order to get into the affordable bottom end of the car market it bought the rights to the Isetta.
BMW replaced the Isetta’s two-stroke with a modified version of one of its motorcycle engines, 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 Iso.
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, 585 cc, 19.5 horsepower two cylinder 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 performance of the Isetta was definitely not freeway friendly. Road & Track magazine (2/58) tested one and recorded a top speed of approximately 50 mph (80 km/h) and a zero to 40 mph (64 km/h) acceleration time of 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 “Dynastart.” Visibility was excellent, akin to a fishbowl, and this turned out to be an important feature. Large potholes would swallow the tiny 10-inch wheels. Parking, of course, is a breeze; simply nose into the curb and step out onto the sidewalk.
Isetta drivers could not be shy or retiring because the car attracted attention everywhere it went. The most often heard enquiry? Is this really a BMW? Many people apparently missed this short chapter in BMW history.
The Isetta and the 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 launching of the 1500, forerunner of the very successful 2002.