- Highly efficient: up to 30 percent more range thanks to energy recuperation
- World premiere in electric cars: the electrohydraulically integrated brake control system
- Strong performance: up to 300kW and 0 to 100km/h in less than six seconds
Colorado Springs, August 9, 2018 – The Audi e-tron prototype combines enormous power and excellent efficiency, with a system output of up to 300kW. The full-size SUV with a fully electric drive accelerates from zero to 100km/h in less than six seconds. In the WLTP test cycle, it covers more than 400 kilometres on one battery charge. One important factor for the long range is the most innovative recuperation concept among the competitors, clearly demonstrated with an impressive performance at Pikes Peak.
The scenario: each kilometre downhill adds around an additional kilometre in range
At 4302 metres, Pikes Peak looms high in the southern Rocky Mountains. It was here that Walter Röhrl won the world's most famous hillclimb in the Audi Sport quattro S1 back in 1987, but it is the Audi e-tron prototype that is now causing a sensation. With its variable recuperation system, it is the most efficient among all the competitors. On its 31 kilometre downhill drive, the electric SUV feeds so much energy back to the battery that it can cover approximately the same distance again. The difference in altitude of about 1900 metres provides the perfect conditions for this. The Audi e-tron prototype recuperates energy with up to 300Nm of torque and 220kW of electric power – more than 70percent of its operating energy input. No series-production model has achieved such a value up to now.
The recuperation concept: from freewheeling to a one-pedal feeling
The recuperation system contributes up to 30 percent of the electric SUV's range. It involves both the two electric motors and the electrohydraulically integrated brake control system. For the first time, three different recuperation modes are combined: manual coasting recuperation using the shift paddles, automatic coasting recuperation via the predictive efficiency assist, and brake recuperation with smooth transition between electric and hydraulic deceleration. Up to 0.3g, the Audi e-tron prototype recuperates energy solely via the electric motors, without using the conventional brake – that covers over 90 percent of all decelerations. As a result, energy is fed back to the battery in practically all normal braking maneouvres.
The driver can select the degree of coasting recuperation in three stages using the steering wheel paddles. At the lowest stage, the vehicle coasts with no additional drag torque when the driver releases the accelerator pedal. At the highest stage, the electric SUV reduces the speed noticeably – the driver can slow down and accelerate using only the accelerator pedal. This creates the one-pedal feeling. There is no need to use the brake pedal in this deceleration scenario.
The wheel brakes are involved only when the driver decelerates by more than 0.3g using the brake pedal. They respond extremely quickly, thanks to a new electrohydraulic actuation concept. Audi is the first manufacturer worldwide to use this concept in a series production vehicle with electric drive. A hydraulic piston in the compact brake module generates additional pressure and thus additional brake force for the recuperation torque. When automated emergency braking is performed, there are only 150 milliseconds between the initiation of the deceleration and the presence of maximum brake pressure between the pads and disks. Thanks to this rapid pressure buildup, the braking distance is shortened by up to 20 percent compared with a conventional brake system.
Depending on the driving situation, the electrohydraulically integrated brake control system decides – electrically on each individual axle – whether the Audi e-tron prototype will decelerate using the electric motor, the wheel brake, or a combination of the two. The brake pedal decouples from the hydraulic system, with the transition from the engine brake to the pure friction brake so smooth that the driver does not notice it. This system allows the electric SUV to exploit its maximum recuperation potential in a targeted manner with support from the standard efficiency assist. The system uses radar sensors, camera images, navigation data and Car-to-X information to detect the traffic environment and the route. The driver is shown corresponding information in the Audi virtual cockpit as soon as it would be sensible to take the foot off the accelerator pedal. By interacting with the optional adaptive cruise assist, the efficiency assist can also decelerate and accelerate the electric SUV predictively.
The asynchronous motors: strong performance
What is fascinating about the electric drive of the e-tron prototype is not just its efficiency but also its performance. Its two electric motors have an output of 265kW and develop 561Nm of torque. They can deliver this peak performance for up to 60 seconds. This way, they allow the vehicle to accelerate from a standstill to the electronically limited top speed of 200km/h several times consecutively without output losses. The maximum drive torque is present within fractions of a second and provides enormous torque. By shifting from drive range D to S and fully depressing the accelerator, the driver can activate boost mode, which is available for eight seconds. Here, the drive produces 300kW of system output and 664Nm of torque, allowing the Audi e-tron prototype to sprint from 0 to 100 km/h in less than six seconds.
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The Audi Group, with its brands Audi, Ducati and Lamborghini, is one of the most successful manufacturers of automobiles and motorcycles in the premium segment. It is present in more than 100 markets worldwide and produces at 16 locations in twelve countries. 100 percent subsidiaries of AUDI AG include Audi Sport GmbH (Neckarsulm), Automobili Lamborghini S.p.A. (Sant'Agata Bolognese, Italy) and Ducati Motor Holding S.p.A. (Bologna, Italy).
In 2017, the Audi Group delivered to customers about 1.878 million automobiles of the Audi brand, 3,815 sports cars of the Lamborghini brand and 55,900 motorcycles of the Ducati brand. In the 2017 fiscal year, AUDI AG achieved total revenue of €60.1 billion and an operating profit of €5.1 billion. At present, approximately 90,000 people work for the company all over the world, more than 60,000 of them in Germany. Audi focuses on sustainable products and technologies for the future of mobility.