Wikipedia: "The Isetta was one of the most successful microcars produced in the post-World War II years—a time when cheap, short-distance transportation was most needed. Although the design originated in Italy, it was built in a number of different countries, including Spain, Belgium, France, Brazil, Germany, and the United Kingdom. Because of its egg shape and bubble-like windows, it became known as a bubble car—a name later given to other similar vehicles.
BMW made the Isetta its own. They redesigned the powerplant around a BMW one-cylinder, four-stroke, 247 cc motorcycle engine which generated 10 kW (13 hp). Although the major elements of the Italian design remained intact, BMW re-engineered much of the car, so much so that none of the parts between a BMW Isetta Moto Coupe and an Iso Isetta are interchangeable. The first BMW Isetta appeared in April 1955."