2/10/2011 | 3 MINUTE READ

Audi Addresses Electromobility

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Coming soon to a dealer near you: a crossover hybrid and a pure-electric R8.


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Audi, the premium brand that has probably done more to obviously bring diesel technology to the segment than any other marque, is aggressively undertaking a program to develop a whole range of alternative powertrains that it is labeling "e-tron." As you can immediately discern, it is about electrification, and the company is developing a full suite of offerings in this space, from hybrids to fully battery-powered cars. And, yes, there is even a hydrogen-powered car in the works.

The center for its e-initiative is a 150,690-ft2 facility at its Ingolstadt site, where some 840 people are dedicated to working on drive systems, batteries, and power electronics. The first vehicle that will become commercially available is the Audi Q5 Hybrid, which is to go on sale in 2011. It will be followed in late 2012 by the R8 e-tron electric sports car.

The Q5 Hybrid utilizes a 2.0-liter TFSI (turbocharged, direct injection) four-cylinder engine that produces 211 hp. It has been slightly modified compared to the version used in vehicles like the Audi TT; for example, there is a secondary air system added at the cylinder head to assure that the exhaust gas treatment kicks in quickly. There is a modified eight-speed tiptronic transmission; it doesn't have a torque converter; the disk-shaped electric motor is located where that would be. A multi-plate clutch couples and decouples engine and motor as required. The engine and electric motor combined have an output of 245 hp and 354.03 lb-ft of torque. There is a 72-cell lithium-ion battery pack located under the load floor such that it is safely located in case of a collision and it has little intrusion in the cargo space. Its nominal energy is 1.3 kWh and its output is 39 kW.

The vehicle has start-stop capability. When the vehicle is at a stop, the HVAC system continues to operate; there is a high-voltage based electric drive for the air conditioner compressor and an auxiliary electric heater. When the brake is released, the vehicle can run on electric power alone (depending on the state of charge of the battery and other parameters) at speeds up to 62 mph and for a distance of 1.86 miles. There are three selectable modes offered to the driver: EV, for providing electric-only priority for driving in the city; D, for optimally controlling consumption for both the engine and motor; S, for sporty driving (e.g., when the accelerator is firmly depressed in the S setting, the engine and the motor both operate at full output). When the driver lifts from the accelerator, the engine is decoupled from the drive line and the electric motor acts as a generator to recharge the battery. There is, of course, regenerative braking.

While the Q5 Hybrid is targeted to the center of the premium market, there is the R8 e-tron, which is for the more rarified. While the Q5 Hybrid is pretty well productionized, the R8 e-tron is still much more of a development vehicle (the former was driven on the roads in and around Ingolstadt; the latter was driven in a parking lot).

The peak output of the R8 e-tron is 313 hp (a.k.a., 230 kW); it produces 3,319 lb-ft of torque (a.k.a., 4,500 Nm).

And its 0 to 62.14 mph (a.k.a., 100 km/h) time is 4.8 seconds.

This is achieved through the deployment of four asynchronous motors, two each for the front and rear axles. There is a single-stage transmission and short input shafts for each of the wheels. The motors can be individually actuated as required by the road conditions and/or driver input—think of it as the next-generation of quattro. Ordinarily, the torque split is 30/70 front/rear. However, there is torque vectoring capability such that compensation for under- or over-steering can be readily accommodated by power boosts to individual motors and braking of individual wheels.

Power is provided by a lithium-ion battery pack that weighs 1,212 lb. It stores a total 53 kWh of energy, of which 42.4 kWh are considered usable. The battery pack is located behind the seats. The range is anticipated to be in the vicinity of 155 miles.

Because electric vehicles tend to be heavy—just look at the mass of the battery pack—Audi's well-established area of expertise comes into play here: the body is aluminum and the Audi Space Frame is deployed for the structure. The result is a vehicle that weighs 3,527 lb. By way of comparison: the R8 5.2 FSI with a six-speed manual weighs 3,571 lb.