Fritz Fend had designed a small tricycle invalid carriage in 1948 that was powered by hand action on the handlebars in 1948. Later a 38cc engine was fitted, before Fend used his war time experience as an aeronautical engineer to design a better model with a 98cc engine. Still intended as an invalid carriage, it also sold to able-bodied people looking for cheap transport. Production of the Fend Flitzer ended in 1951 by which time Fend had signed an agreement with Messerschmitt to produce a better 2-seater tandem device (Fend Kabinenroller FK-150) as the Messerschmitt KR175 in 1953. Production was overseen by Professor Messerschmitt at his Regensburger Stahl- und Maschinenbau (RSM) plant in Regensburg, Germany. Powered by a Fichtel & Sachs 175cc 2-stroke engine, the KR175 design had many problems and was revised for 1954. The KR200 was launched in 1955 with a 191cc engine and the car was a new design with wider track, new rear suspension, more luxury inside. Permitted to build aircraft once more, Messerschmitt sold the Kabinroller project to a consortium called Fahrzeug und Maschinenbau (FMR) which included Fritz Fend. Cars were still marketed as Messerschmitt, but from 1957 now carried an FMR badge in place of the Messerschmitt bird. Design changes came in 1959 with a revised rear swing arm, dynastart electrics, and more comfort. A cabrio model (KR200) was launched in 1957, and a stripped down KR201 Roadster. From 1958 to 1961 the FMR Tg500 (often known as the 'Tiger') was produced having a 4-wheel configuration, and powered by a new 493cc Fichtel & Sachs twin cylinder engine. However, it cost more than an Austin-Healey 'Frogeye' Sprite and performance was not quite as good. Sales ended in 1964 when the Bubble Car boom ended.