The Sinclair C5 is a small one-person battery electric vehicle, technically an "electrically assisted pedal cycle". It was the culmination of Sir Clive Sinclair's long-running interest in electric vehicles. Although widely described as an "electric car", Sinclair characterised it as a "vehicle, not a car".

Sinclair had become one of the UK's best-known millionaires, and earned a knighthood, on the back of the highly successful Sinclair Research range of home computers in the early 1980s. He hoped to repeat his success in the electric vehicle market, which he saw as ripe for a new approach. The C5 emerged from an earlier project to produce a Renault Twizy-style electric car called the C1.

The C5 became known as "one of the great marketing bombs of postwar British industry" and a "notorious ... example of failure". Despite its commercial failure, the C5 went on to become a cult item for collectors. Thousands of unsold C5s were purchased by investors and sold for hugely inflated prices – as much as £5,000, compared to the original retail value of £399. Enthusiasts have established owners' clubs and some have modified their vehicles substantially, adding monster wheels, jet engines, and high-powered electric motors to propel their C5s at speeds of up to 150 miles per hour (240 km/h).

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