Audi R8 e-tron

The Audi R8 e-tron is a high-performance sports car with electric drive. Its four electric motors – two on the front axle and two on the rear – are connected to the wheels by short shafts. With a maximum power output of 230 kW (313 hp) and 600 Nm (442.54 lb-ft) of torque available from stationary, the R8 e-tron accelerates from 0 to 100 km/h (62.14 mph) in 4.8 seconds; its top speed is limited to 200 km/h (124.27 mph).

The technology demonstrator inside the body of the Audi R8, which Audi plans to build on a small scale from the end of 2012, is among the very finest electric sports cars. Its package does justice to the specific qualities of the new technology in every detail. The large, liquid-cooled lithium-ion battery and the power electronics lie directly behind the passenger compartment.

This arrangement produces an optimal center of gravity and a weight distribution of 42:58 between the front and rear axles.

The lithium-ion battery in the Audi R8 e-tron consists of a large number of individual cells of high energy density that are wired together. The 550 kilogram (1212 lb) battery stores 53 KWh of energy, with an effective 42.4 kWh of power – enough to cover about 250 km (155 miles) according to the NEDC cycle. When the battery is entirely discharged, it takes between six and eight hours to charge it up from a 230V supply; with a heavy current supply the process takes around two and a half hours. The battery is also recharged by means of recuperation from braking and retardation phases. The driver can select the degree of energy recovery at shift paddles on the steering wheel.

The drive torque acts largely on the rear axle, which in regular operating conditions receives 70 percent of the propulsive power. If slip occurs at one pair of wheels, the way the power is distributed changes with lightning speed. The Audi R8 e-tron also manages the transverse dynamics through its four motors. They allow torque vectoring, the selective acceleration of individual wheels and therefore active distribution of torque. Understeer and oversteer can be compensated for very precisely by means of small increases in power and braking interventions – the quattro drive system thus reaches the new evolutionary level of an electric quattro.

Systematic lightweight construction is particularly important for electric vehicles. The body of the Audi R8 e-tron is aluminum; designed with Audi Space Frame technology (ASF), it weighs less than 200 kilograms (441 lb). This is an important reason why the electrically powered high-performance sports car weighs in at just 1500 kilograms (3307 lb).

Source: Audi press

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