Sinclair Vehicles

Sinclair C5

The Sinclair C5 is a small battery electric one-person recumbent tricycle, technically an "electrically assisted pedal cycle". It was the culmination of the English entrepreneur 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, for his successful Sinclair Research range of home computers in the early 1980s. He hoped to repeat his success in the electric vehicle market, which he thought had potential for a new approach. The C5 emerged from an earlier project to produce a small electric car called the C1. After a change in the law, prompted by lobbying from bicycle manufacturers, Sinclair developed the C5 as an electrically powered tricycle with a polypropylene body and a chassis designed by Lotus Cars. It was intended to be the first in a series of increasingly ambitious electric vehicles, but the development of the follow-up C10 and C15 models never progressed, mostly due to the poor public response to the C5. On 10 January 1985, the C5 was unveiled at a launch event, but it was received unenthusiastically by the British media. Its sales prospects were blighted by poor reviews and safety concerns expressed by consumer and motoring organisations. The vehicle's limitations – a short range, a maximum speed of only 15 miles per hour (24 km/h), a battery that ran down quickly and a lack of weatherproofing – made it impractical for most people's needs. It was marketed as an alternative to cars and bicycles, but ended up appealing to neither group of owners, and it was not available in shops until several months after its launch. Within three months of the launch, production had been slashed by 90%. Sales never picked up despite Sinclair's optimistic forecasts and production ceased entirely by August 1985. Out of 14,000 C5s made, only 5,000 were sold before its manufacturer, Sinclair Vehicles, went into receivership. The C5 has been described as "one of the great marketing bombs of postwar British industry" and a "notorious ... example of 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 £6,000 compared to the original retail value of £399. Enthusiasts have established owners' clubs and some have modified their vehicles substantially, adding bigger 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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Design

The C5 is made predominantly of polypropylene, measuring 174.4 cm (68.7 in) long, 74.4 cm (29.3 in) wide, and 79.5 cm (31.3 in) high. It weighs approximately 30 kg (66 lb) without a battery and 45 kg (99 lb) with one. The chassis consists of a single Y-shaped steel component with a cross-section of about 5.5 by 4 cm (2.2 by 1.6 in) The vehicle has three wheels, one of 317 mm (12.5 in) diameter at the front and two of 406 mm (16.0 in) at the rear. The driver sits in a recumbent position in an open cockpit, steering via a handlebar that is located under the knees. A power switch and front and rear brake levers are positioned on the handlebar. As a supplement to or replacement for electric power, the C5 can also be propelled via bicycle-style pedals located at the front of the cockpit. The maximum speed of an unmodified C5 is 15 miles per hour (24 km/h). At the rear of the vehicle is a small luggage compartment with a capacity of 28 litres (1 cu ft). As the C5 does not have a reverse gear, reversing direction is done by getting out, picking up the front end and turning it around by hand. The C5 is powered by a 12-volt lead–acid electric battery driving a motor with a continuous rating of 250 watts and a maximum 4,100 revolutions per minute. It is coupled with a two-stage gear-drive that increases torque by a factor of 13, without which the motor would not be able to move the vehicle when a person is on board. However, the motor is vulnerable to overheating. The torque increases as the load on the vehicle increases, for instance by going up too steep a gradient. Sinclair's tests showed that it could cope under power with a maximum slope of 1 in 12 (8%) and could manage a 1 in 7 (14%) slope using the pedals. As the speed of the motor reduces, the current flow through its win

History

=== Origins === Sir Clive Sinclair's interest in the possibilities of electric vehicles originated in the late 1950s during a holiday job for the electronics company Solartron. Fifteen years later, in the early 1970s, he was the head of his own successful electronics company, Sinclair Radionics, based in St Ives in Cambridgeshire. He tasked one of his employees, Chris Curry – later a co-founder of Acorn Computers – to carry out some preliminary research into electric vehicle design. Sinclair took the view that an electric vehicle needed to be designed from the ground up, completely rethinking the principles of automotive design rather than simply dropping electric components into an established model. He believed that the motor was the key to the design. Sinclair and Curry developed a wafer-thin motor that was mounted on a child's scooter, with a button on the handlebars to activate it. The research got no further, however, as Sinclair's development of the first "slimline" pocket calculator – the Sinclair Executive and its successors – took precedence. No further work on electric vehicles took place for most of the rest of the 1970s. Early development: the C1. It was not until late 1979 that Sinclair returned to electric vehicle development. Around Christmas that year, he approached Tony Wood Rogers, an ex-Radionics employee, to carry out consultancy work on "a preliminary investigation into a personal electric vehicle". The brief was to assess the options for producing a one-person vehicle which would be a replacement for a moped and would have a maximum speed of 30 miles per hour (48 km/h). Although Wood Rogers was initially reluctant, he was intrigued by the idea of an electric vehicle and agreed to help Sinclair. The vehicle was dubbed the C1 (the C standing for Cli

Legacy

=== Sinclair's other electric vehicles === Sinclair envisaged producing follow-up vehicles such as the C10, a two-seater city car, and the C15, a three-seater capable of travelling at 80 miles per hour (130 km/h). As Wills put it at the launch event, "We're developing a family of traffic-compatible, quiet, economic and pollution-free vehicles for the end of the '80s." The C5 was described as "the baby of the family". The C10 was intended to be a city car, capable of carrying two passengers at up to 40 miles per hour (64 km/h) in a roofed but open-sided compartment with two wheels at the front and one at the back. Wood Rogers intended it to effectively be an updated version of the Isetta, a 1960s Italian microcar. Sinclair built a full-scale mock-up of it; according to Wood Rogers, "it looked great. I specified open sides to keep the cost down and having no doors meant it escaped a lot of regulations too." The design is strikingly similar to the modern Renault Twizy electric vehicle; Wood Rogers comments that "you could put the C10 into production today and it would still look contemporary." At the time of the C5's launch, Sinclair described the C15 as having "a futuristic design with an elongated 'tear-drop' shape, a lightweight body made of self-coloured polypropylene and a single, possibly 'roller' type rear wheel". It would have been launched at the 1988 International Motor Show in Birmingham following a development programme costed at £2 million. Unlike the relatively conventional technology used in the C5, Sinclair intended to use sodium sulphur batteries with four times the power-to-weight ratio of lead–acid batteries to give the C15 much greater speed and range – over 180 miles (290 km) on a single charge. It would have had approximately the same dimensions as a

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Specifications

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Sources

• Wikidata — https://www.wikidata.org/wiki/Q1429206CC0 1.0 · retrieved 2026-10-01
• Wikipedia — https://en.wikipedia.org/wiki/Sinclair_C5CC BY-SA 4.0 · Text © Wikipedia contributors; revision 1375504897 · retrieved 2026-10-01
• Wikimedia Commons — https://commons.wikimedia.org/wiki/File:SinclairC5-side.jpgCC BY 2.0 · Photo: Grant Mitchell · retrieved 2026-10-01
• Car Model Index — https://models.autoculturesociety.com/Compiled record. Sources that do not permit reuse are not copied; this index is credited instead.