210km/h electric sportscar will be built in the UK

A battery-powered sportscar that can reach 60mph (96km/h) in four seconds, hit a top speed of more than 130mph (210km/h) and travel for 250 miles (402km) on one charge, is being built in the UK for a Californian company, Tesla Motors.

The Tesla Roadster (shown above, with California`s governor, Arnold Schwarzenegger, in the passenger seat) is due to go on sale in the US next year for around $90,000. It is being assembled in Norfolk by Lotus using components sourced from around the world. For instance, the car`s 185kW three-phase, four-pole induction motor (shown below) is being built by Tesla in Taiwan. The motor, with a brazed copper and steel rotor, has a top speed of 13,500 rpm and can deliver 244Nm of torque. Its efficiency is said to be 95%, compared to 20% for a typical internal combustion engine.

The rear-wheel-drive Roadster — which looks similar to Lotus` Elise — has a two-speed, electrically-actuated manual gearbox, and incorporates regenerative braking. There is no clutch. Torque adjustments and speed matching for gear changes are done by software. Because of the motor`s ability to run in either direction, there is no need for the extra weight of a reverse gear — a simple switching arrangement is used. An air-cooled power electronics module acts as an inverter to drive the motor and controls charging at up to 70A, 240V.

The Roadster`s 6,831 water-cooled lithium-ion cells can be recharged in 3.5 hours. Its running costs are estimated at 1-2 cents/mile - or less when a planned solar panel charger becomes available.

Tesla Motors is planning further electric cars, including a four-door saloon which it hopes to start selling in 2008 for less than $50,000.

Tesla, which was set up three years ago, has attracted $40m of funding from backers including Google founders Sergey Brin and Larry Page, as well as personalities involved in setting up eBay and PayPal.

A former Lotus engineer, Malcolm Powell, is overseeing Tesla`s manufacturing. Several other former Lotus employees have joined Tesla and the Norfolk company is reported to have demanded a no-poaching agreement before agreeing to build the Roadster.

• Another UK company, Lichfield-based Zytek, is building an electric version of DaimlerChrysler`s Smart car, which was unveiled at the recent London Motor Show. Zytek has designed the drivetrain based on a 55kW brushless DC motor that delivers 120Nm peak torque. The drivetrain, including motor, gearbox, inverter and control electronics, weighs 70kg. The electric Smart, powered by a liquid sodium nickel chloride battery, will have a range of 116km (72 miles) and an electronically limited top speed of 113km/h (70mph). Running costs, at €0.02/km, are a third of the petrol-driven equivalent. Up to 200 electric Smarts are being built for trials with corporate customers in the UK.