On January 10th, 1985, Sir Clive Sinclair, the knighted millionaire behind the pocket calculator and the ZX Spectrum, unveiled what he believed was the future of transport at Alexandra Palace in London. It was a three-wheeled, open-air electric vehicle that looked like a plastic bathtub. This episode follows the Sinclair C5 from his long obsession with electric vehicles, through his sale of about 8.3 million pounds in personal shares to fund a secretive new company, to a launch in snow and ice that journalists turned into a public humiliation.

The root of the trouble was a 1983 UK legal category, the electrically assisted pedal cycle, which required no license, insurance, road tax, or helmet. To qualify, the C5 could weigh no more than 60 kilograms, use no more than a 250 watt motor, and travel no faster than 15 miles per hour. Sinclair designed for the loophole instead of the commuter, with almost no market research. The collapse took eight months, yet the unsold stock found a strange afterlife, and the idea itself now looks decades early.

• The C5 ran on a standard lead acid battery and a motor originally designed to drive a truck cooling fan, and it was assembled in a Hoover washing machine factory in Wales.
• At the launch, cold cut the advertised 20 mile range to around five, and racing driver Stirling Moss was reduced to pedaling uphill amid diesel fumes.
• The British Safety Council chairman said he was shattered that 14-year-olds could drive it in traffic without a license, insurance, or a helmet.
• Production ended by August 1985 with about 5,000 of 14,000 units sold, and Sinclair lost seven million pounds of his own fortune.
• Liquidated C5s bought for as little as 75 pounds became collector’s items, and one modified example ran at 150 miles per hour.