A microcar is an extremely small automobile, popularly referred to as cyclecars in the 1910s and 1920s and bubblecars in the 1950s and 1960s, many of which are also three wheeled. Various definitions are used, including "less than 3 metres in length" and "less than 85 cubic feet/2400 litres interior volume". Most definitions seem to involve multiple parameters and of those, engine size (or lack of) is very important. The Register of Unusual Microcars in the UK says: "economy vehicles with either three or four wheels, powered by petrol engines of no more than 700cc or battery electric propulsion, and manufactured since 1945".
The Bruce Weiner Microcar Museum (the world's largest collection of Microcars) says "Engine sizes of 700cc and less and 2 doors or less" and The US-based Vintage Microcar Club simply defines it as 1000cc or less.
Typically, microcars seat only the driver and a single passenger, and many have only three wheels. Microcars are usually designed and produced for economic purposes when materials and heavy equipment are scarce or fuel is scarce and expensive.
Another name for microcar is Station Car, where the intended use is to travel from a suburban home to an interurban transit station or Park and Ride lot where the vehicle remains until the operator returns from the commute to and from the workplace. In some locations electric vehicle recharging is provided to encourage the use of electric vehicles. NEVs (Neighborhood Electric Vehicles) may also be used as station cars where the roadway speed limits permit such use. These vehicles are also referred to as Autoette (or Auto-ette) in some vehicle regulations, such as those of the city of Avalon, California on Catalina Island.
There are also a variety of microcar trucks, usually of the "forward control" or van style to provide more cargo room. These might be used for local deliveries on narrow streets where standard small pickup trucks would be inconvenient, and full-sized delivery trucks would be impossible.
Many microcar designs flourished in post-World War II Europe, particularly in Germany, where former military aircraft manufacturers such as Messerschmitt and Heinkel were prominent microcar makers. The Messerschmitt KR175, KR200 and TG500 even had aircraft-style bubble canopies, giving rise to the term bubble car to refer to all these post-war microcars. Isettas and others also had bubble-like appearance.
In the 1960s, the smallest car ever, Peel P50 was made.
France also produced large numbers of similar tiny vehicles called voiturettes, but unlike the German makes, these were rarely sold abroad. Very small cars have also been popular in Japan, where again they attract various tax and insurance benefits when compared to other vehicles. These are known as keicars and differ from most of the European microcars in that they are typically designed and built as scaled-down versions of very traditional car configurations, while European microcar designs tend to be unorthodox and sometimes bizarre.
The Smart (model Fortwo) launched in 1998 could be seen as a successful re-invention of the microcar (or at least the city car) principle. Like the Japanese keicars, it is of relatively conventional design.
In some countries, microcars with a certain maximum weight are considered motorcycles and therefore no car driving licence is needed (Austria, France, Germany, Spain, Portugal, Italy). This assuring a certain market for elder people who did not want to pass a car driving licence. More negatively, at least in Austria and France, such cars are sometimes derided as a solution for people who had their licence revoked because of drunk driving.
Three wheelers are a separate class of their own in Britain.
In some European countries, taxes used to depend on engine displacement and/or insurance on power. This has given rise to names of such cars as Citroën 2CV and Renault 4CV. This favourable treatment by governments is based on the benefits to a society of reducing use of such resources as minerals, parking space and foreign exchange, reduced noise and chemical pollution, reduced hazard to others (they are slow vehicles) etc. Reduced global warming from carbon dioxide emission has now been added to this list.
Another advantage is the ease of parking. Some microcars can be parked perpendicular, where other cars park parallel, or be lifted by hand, like a motor scooter, to get into a tight spot. The Isetta and some others had forward entry, to facilitate perpendicular parking close to other vehicles. The Corbin Sparrow is licensed as a motorcycle and parked in motorcycle spaces in California, and probably in other places.
The small size improves handling by reducing the angular inertia. The Messerschmitt and Spatz have been described as much better than ordinary cars on snow and ice. Spare room on the road and ease of missing obstacles are also improved.
For the performance oriented, who prefer more than two wheels and a roof, the scaling laws show that one need not give up acceleration until the curb weight comes down to around the driver's weight, because power per weight of the car itself improves with small size, in an otherwise similar design. Top speed is lost with small scale, due to the decreased Reynolds number, but this is a small effect. The Messerschmitt TG500 had about a 142 km/h (90 mph) top speed with 15 kW (20 horsepower) and excellent aerodynamics.
Some examples of battery electric microcars are:
The obstacle to adaptation of such vehicles in the United States is less technical than cultural and political. The mandates by regulatory powers that such vehicles meet full U.S. safety regulations ensures the unavailability of vehicles suitable for use in the mixed traffic conditions that predominate in U.S. suburban areas.