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Sunday, December 13, 2009

2012 Audi E-tron TEST DRIVE

A couple of Senior Editor over at were recently invited to test drive a $2 Million concept prototype of the All Wheel Drive fully electric Audi e-tron. The test drive was limited to 62 mph and lasted only 5 miles but they were allowed on public roads along California's Pacific Coast Highway just north of Malibu at Point Magu flanked by 2 highway patrol cars.

Good to read that Audi has almost come clean on the headline grabbing torque figures they've been announcing for the e-tron. We picked up on this way back when the car was first unveiled in October while the rest of the motoring media have taken a little longer to catch on.

Audi now say the reduction gear ratios for the four in-board wheel motors are 6:1 at the front and 7:1 at the rear. To give you a comparison, the hand wound 3 phase AC Induction motor in the Tesla Roadster Sport puts out 400 Nm of torque at the motor shaft. To calculate torque at the wheels simply multiply that torque figure by the reduction gear ratio, which in the case of the Roadster is 8.27:1. There are fairly significant losses transmitting power through a gearbox but for now we'll ignore those. The result is a theoretical 3308 Nm of torque at the rear wheels.

A more every day example to compare against the Audi is a car like a Holden Commodore (Pontiac G8). These come standard with a 5.7 lt LS1 V8 engine that puts out approx 475 Nm at the flywheel. In first gear this garden variety 4 door family sedan has 4476 Nm at the rear wheels.

Audi are still sticking to their guns by quoting torque output at the wheels instead of the motor shaft but with some minor math we can at lease have an educated guess at the real numbers now.

According to the media test drivers the concept e-tron was unable to keep up with the Dodge Challenger Highway Patrol cars escorting it so we're guessing the demo vehicle was quite a bit short of the 4500 Nm (3,319 ft/lb) claimed in press releases.

Still, what an awesome piece of automotive technology and we can't wait to see what Audi's engineers, the crew that introduced all wheel drive to World Championship rallying and built the S1, can do with the sports cars dynamic performance using torque vectoring across four independent wheel motors!

Read the reviews here and here

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