Performance of a genuine sports car.The drivetrain of the Detroit showcar Audi e-tron.

Two asynchronous electric motors with a total output of 150 kilowatts (204 hp) give the Detroit showcar Audi e-tron the performance of a genuine sports car. The concept car can accelerate from 0 to 100 km/h (0 – 62.14 mph) in 5.9 seconds if necessary, and goes from 60 to 120 km/h (37.28 – 74.56 mph) in 5.1 seconds. The torque is distributed selectively to the wheels based on the driving situation and the condition of the road surface, resulting in outstanding traction and handling.

The top speed is limited to 200 km/h (124.27 mph), as the amount of energy required by the electric motors increases disproportionately to speed. The range in the NECD combined cycle is approximately 250 kilometers (155.34 miles).

The energy storage unit is charged with household current (230 volts, 16 amperes) via a cable and a plug. The socket is behind a cover at the back of the car. The charging time when the battery is empty is around 11 hours, but heavy current (400 volts, 32 amperes) cuts this to around just two hours.

The battery is charged not only when the car is stationary, but also when it is in motion. The keyword here is recuperation. This form of energy recovery and recharging of the battery is already available on many Audi production models. During braking, the alternator converts the kinetic energy into electrical energy, which it then feeds into the on-board electrical system.

The Detroit showcar Audi e-tron in its further developed version goes one decisive step further into the future; an electro-mechanical brake system means the potential of electric motors for energy recovery can now be exploited. A hydraulic fixed-caliper brake is mounted on the front axle, with two novel, electrically actuated floating-caliper brakes mounted on the rear axle. These floating calipers are actuated not by any mechanical or hydraulic transfer elements, but rather by wire (“brake by wire”). In addition, this eliminates frictional losses due to residual slip when the brakes are not being applied.

By virtue of being isolated from the brake pedal, the Audi e-tron’s electric motors can convert the entire deceleration energy into electric current and recover it. The electromechanical brake system is only activated if greater deceleration is required. These control actions are unnoticeable to the driver, who feels only a predictable and constant pedal feel as with a hydraulic brake system.

An automotive first: the heat pump
The heat pump, too – which made its first appearance in an automobile on the Audi e-tron concept car shown in Frankfurt – helps to boost efficiency and range. Unlike a combustion engine, the electric drive system generally does not produce enough waste heat to effectively heat the interior. Other electric vehicles are equipped with electric supplemental heaters, which consume a relatively large amount of energy. The heat pump used by Audi – and commonly used in buildings – is a highly efficient machine that uses mechanical work to provide heat with a minimum input of energy.

A high-efficiency climate control system is used to cool the interior. It works together with the thermal management system to also control the temperature of the high-voltage battery. This is because the battery, power electronics and electric motors must be kept at their respective ideal operating temperatures to achieve optimal performance and range.

As soon as the vehicle is connected to a charging station the vehicle is preconditioned as appropriate by the thermal management and other associated systems. In cold conditions the drive system is preheated, and in hot conditions it is cooled. This preconditioning can also be extended to the interior, if necessary, so that the passengers can step into a cabin that has been heated or cooled as appropriate for their comfort.