Sinclair C5 was the worst product of the 1980s — and it bankrupted Sir Clive

Sir Clive Sinclair, the British inventor who popularised home computers with the ZX Spectrum, launched the C5 in January 1985. It was a battery-assisted recumbent tricycle with a polypropylene body, a 250W motor, and a top speed of 15 mph. Sinclair invested £8.3 million in development and spent £3 million on advertising, promising a revolution in personal transport.

The C5 was a disaster from the start. The launch demo vehicles had flat batteries and could not climb the hill at Alexandra Palace. Safety campaigners warned that the vehicle was invisible to truck drivers and dangerously unstable on turns. The short range — about 10 miles in practice — and lack of weather protection made it impractical. Production was halted after three weeks because of faulty gearbox mouldings, and resumed at only 10% capacity.

Of 14,000 units produced, only about 5,000 were sold before Sinclair Vehicles went into receivership in October 1985. The company had debts of £7.75 million, most of it owed to Sinclair himself. The unsold stock was sold to a liquidator at £75 each. The C5 failure ended Sinclair's electric vehicle ambitions and was a major personal financial blow to the inventor of the ZX Spectrum.