Audi AG’s E-tron electric vehicle unveiled at the Frankfurt auto show packs in four electric motors – two at each axle – to provide the concept sports car with all-wheel-drive and torque-vectoring capability.
The individual wheel motors mark just one of several innovations Audi demonstrates in the new concept.
Fueled by a 48 kWh lithium-ion battery pack with a range of 154 miles (248 km), the 2-seater can accelerate from a standstill to 62 mph (100 km/h) in 4.8 seconds thanks to its combined output rating of 230 hp and 3,319 lb.-ft. (4,500 Nm) of torque. Top speed is 124 mph (200 km/h).
It takes six to eight hours to replenish a fully discharged battery, but that can be cut to 2.5 hours using a high-voltage line.
On the road, the four asynchronous motors supply torque individually and automatically to each wheel as needed depending on road conditions.
To maximize range, Audi says it focused on light-weight construction and an aerodynamic shape for the E-tron. The body is structured around the Audi Space Frame technology used for the R8 and employs carbon-fiber-reinforced plastic for all add-on parts, such as the roof, doors and sidewalls. Audi says it soon will use this construction technology for a production vehicle.
High-efficiency light-emitting-diode technology is utilized for all lighting. Illumination adapts automatically to weather conditions, lane position and oncoming traffic, using information supplied by an onboard camera.
For instance, high beams automatically will be turned off if there is oncoming traffic, and the lights will steer around corners based on information from the navigation system. There are no conventional fog lamps, because the system can intelligently vary low beams to widen illumination in inclement weather.
The ceramic brake system consists of a hydraulic fixed-caliper brake mounted on the front axle, with two electrically actuated floating-caliper brakes mounted on the rear axle and controlled by wire.
Audi says the decoupling of the brake pedal enables the E-tron’s electric motors to convert all braking energy into electricity and recover it to charge the battery on the fly. The electromechanical brake system is activated only if greater deceleration is required.
A heat pump, similar to that used in some homes is employed for the first time in an automobile to heat the cabin when needed.
The car measures 74.8 ins. (190.0 cm) wide, 167.7 ins. (426.0 cm) long and is 48.4 ins. (122.9 cm) high, and rests on a 102.4-in. (260.1-cm) wheelbase. The water-cooled battery pack is mounted directly behind the passenger cabin, a location Audi says provides the optimum in axle load distribution and center of gravity.
The two electric motors on the rear axle have their own cooling system, as does the pair on the front axle. The positioning helps give the car its 42:58 weight distribution. The E-tron weighs 3,527 lbs. (1,600 kg).
Inside, Audi opts for a steering-wheel-mounted scroll pad (similar to that on a smart phone) to control the man-machine interface. Nearly all conventional switches have been eliminated.