The A-segment is the first category in the passenger car classification system defined by the European Commission. It is used for city cars, the smallest category of passenger cars defined.

Kei car is the smallest category of Japanese, expressway-legal motor vehicles. 'Kei' is diminutive for kei-jidōsha,, "light automobile" or "compact automobile". With restricted dimensions and engine specifications, owners benefit firstly from lower taxes and insurance rates which lead to a lower overall cost of ownership. And in most rural areas, importantly, they were also exempted from the general Japanese shako shōmeisho (車庫証明書) parking-space ownership requirement to legally buy a motor vehicle at all, as street parking is generally restricted in Japan. Japan's carmakers also make microvans and kei trucks within this legal category.