The Isetta is an Italian-designed microcar built under license in a number of different countries, including Argentina, 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 also given to other similar vehicles.
In 1955, the BMW Isetta became the world's first mass-production car to achieve a fuel consumption of 3 L/100 km (94 mpg‑imp; 78 mpg‑US). It was the top-selling single-cylinder car in the world, with 161,728 units sold.
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.