Audi e-tron concept. Click image to enlarge
Audi e-tron concept
Detroit, Michigan – After revealing an electric sports car based on the R8 at the Frankfurt Motor Show, Audi has unveiled a second version of this car with a shorter wheelbase. Also called the Audi e-tron, this electric sports car has two electric motors with a combined output of 204 hp and 1954 lb-ft of torque to accelerate the lightweight coupe with ASF-design aluminum body from 0 to 100 km/h in just 5.9 seconds. The Audi e-tron accomplishes the sprint from 60 to 120 km/h in a mere 5.1 seconds.
Thanks to its low weight, short wheelbase and even weight distribution for dynamic handling, the Audi e-tron has the drivability of a go-kart – “agile, good on bends and neutral right up to the very high handling limit,” says the company.
Lithium-ion batteries, located for an optimal centre of gravity behind the passenger compartment and ahead of the rear axle, make an effective energy content of 45 kilowatt-hours available. This makes an operating range of up to 250 kilometres possible.
The battery can be 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. During braking, the alternator converts the kinetic energy into electrical energy, which it then feeds into the on-board electrical system. The Audi e-tron goes one decisive step further with an electro-mechanical brake system: 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.
Top speed is limited to 200 km/h as the amount of energy required by the electric motors increases disproportionately to speed.