The Isetta is an Italian-designed microcar built under license in a number of different countries. 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. The BMW Isetta widely differed from the Iso model. 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. BMW changed the powerplant to a one-cylinder, four-stroke, 247 cc motorcycle engine of their own manufacture which generated 12 PS (8.8 kW)