The Standard Ten was a model name given to several small cars produced by the British Standard Motor Company between 1906 and 1961. The name was a reference to the car's fiscal horsepower, a function of the surface area of the pistons. This system quickly became obsolete as an estimate of the power produced by the engine, but it continued to be relevant as a way to classify cars for tax purposes. Like other manufacturers, Standard continued to use the name to define the approximate size of their 'Ten' model long after the origins of the name had, in Britain, become inapplicable.