The term light car is used in Great Britain since the early part of the 20th century for an automobile less than 1.5-litres (or about 90 cubic inches) engine capacity. In modern car classification this term would be roughly equivalent to a subcompact car. There are numerous light car clubs in Britain and Australia.
The current UK Driving Licence has the following definition : Light vehicles and quad bikes, Category B1 , You can drive motor vehicles with 4 wheels up to 400 kg unladen or 550 kg if they’re designed for carrying goods.