Sinclair C5 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
Sinclair Scientific fraction of the cost of competing calculators. In 1972, Hewlett-Packard launched the HP-35, the world's first handheld scientific calculator. Despite market research suggesting that it was too expensive for there to be any real demand, production went ahead. It cost (about ), but despite the price, over 300,000 were sold in the three and a half years for which it was produced. From 1971 Texas Instruments had been making available the building block for a simple calculator on a single chip and the TMS0803 chipset appeared in a number of Sinclair calculators. Clive Sinclair wanted to design a calculator to