Electric Sports Car with Four Engines - Audi Presents the "e-tron"

At the IAA in Frankfurt (Germany) Audi has introduced the new high-performance sports car "e-tron" with a purely electric drive system. Four motors - two each at the front and rear axles - propel the two-seater. Producing 230 kW and 4,500 Newton metres of torque, the concept car accelerates from 0 to 100 km/h in 4.8 seconds.
Energy is provided by a lithium-ion battery housed directly behind the passenger cabin. It provides a useable energy content of 42.4 kWh - total energy content is roughly 53 kWh - to enable a maximum range of approximately 248 kilometres, Audi states.

The energy storage unit can be charged with household current (230 V, 16 A) via a cable and a plug. With the battery fully discharged, the charging time is - according to Audi - between six and eight hours. A high voltage (400 V, 63 A) could reduce this to around 2.5 hours. At the same time the Audi engineers are working on a wireless solution and intend to make charging more convenient. An inductive charging station could be activated automatically when the vehicle is docked and it could be placed in the garage at home or also in special parking garages. Such technology is already used today in a similar form to charge electric toothbrushes.

By using recuperation the battery is charged not only when the car is stationary, but also when it is in motion. During braking, the alternator converts the kinetic energy into electrical energy, which it then feeds into the onboard electrical system. An electronic brake system taps into the recuperation potential of the electric motors. A hydraulic fixed-caliper brake is mounted on the front axle, with two electrically-actuated floating-caliper brakes mounted on the rear axle. These floating calipers are actuated not by mechanical or hydraulic transfer elements, but rather by wire. Therefore frictional losses due to residual slip when the brakes are not being applied could be reduced.

Unlike a combustion engine, the electric drive system may not produce enough waste heat under all operating conditions to effectively heat the interior. Therefore Audi installed a heat pump that uses mechanical work to provide heat. A 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. 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. The drive system is heated if temperatures are cool, and cooled if hot.

The 1.90 metres wide, 4.26 metres long and 1.23 metres tall concept sports car is based on lightweight construction and therefore all add-on parts - doors, covers, sidewalls and roof - are made of a fiber-reinforced plastic. Audi states that the combination of aluminium and carbon fiber-reinforced composite material makes it possible to increase rigidity while at the same time reducing weight. According to statements of the car manufacturer the engineers intend to use this technology in the near future in a similar form for production vehicles as well.