3319lb ft of torque - ten times more than the petrol car

Audi pulled off one of the shocks of the 2009 Frankfurt motor show with this, the E-tron. It’s an electric supercar that bears a pretty strong resemblance to the R8 and despite its alternative power source, its performance isn’t far off the more conventional car. That’s thanks to four electric motors – two front and two rear, to give the E-tron a novel take on quattro all-wheel drive – produces a total of 309bhp and 3319lb ft. While the former is over 100bhp off a V8-engined R8 the latter is a stonking ten times bigger than the petrol car’s torque output. It’s unlikely to hit the road all at once, with torque vectoring used to distribute grunt across the four electric motors and to each wheel as required. This aids the dynamics as well as acting as a safety system. The default power balance sees a 70/30 rearward bias, instilling a healthy dose of performance car into the E-tron.

   Its suspension comes in the shape of triangular double wishbones at the front and trapezoidal wishbones rear, with a ‘taut setup’ for the springs and shock absorbers. Performance figures aren’t quite a match for an eight-cylinder R8 – 0-100kph takes 0.2sec longer at 4.8sec, while the top speed is somewhat down at a limited 200kph (compared to 300kph). That’s all down to the complexities of electric power, as the two cars share near-identical dimensions and circa 1600kg kerb weights. Quite an achievement for the E-tron, which has the handicap of a 470kg battery to contend with. It works around that with a host of weight-saving technology. The car’s main aluminium space frame structure is covered in carbon fibre-reinforced plastic body panels, to couple rigidity with low weight. It’s a concept that’ll soon filter down to Audi’s regular production range, apparently. Aerodynamic technology features heavily, too, with the car’s main air intakes opening and closing as required, meaning they can be closed flush under most circumstances to provide a lower, slipperier body.

The battery is placed in front of the rear axle, with the aim of giving the E-tron the dynamics of a mid-engined sports car, and is partly responsible for a 48:52, front:rear weight distribution. It’s a water-cooled item and Audi claims a 250km average range, with a full charge taking 6-8 hours from a normal household socket. The ceramic brake discs can also provide regenerative braking energy. Audi admits that electric cars are still seen as outsiders, but is ploughing a load of money into developing no-compromise electric drive systems.