Audi puts the e-Tron's 0-to-62 mph time at 4.8 seconds -- that's 0.2 second behind the R8 V-8 -- but top speed is limited to only 124 mph, as higher speeds rapidly drain the battery. (More restrictive speed limiting apparently looms as a potential downside to our electric future.) For the e-Tron, Audi is claiming a 154-mile range.

Continuing the R8 comparison, the e-Tron is about 7 inches shorter in length, half-a-foot narrower, and an inch lower. It uses an aluminum spaceframe and fiber-reinforced plastic for the doors, roof, fenders, and lids. The advertised curb weight is 3527 lbs, 58 percent of which is over the rear axle. An R8 V-8 is about 90 lbs lighter. In the e-Tron, the battery accounts for 1036 lbs of its total.

Like all other Audis, the e-Tron is four-wheel drive, although in this case it's by means of four electric motors, two for each axle. The default set-up sends 70 percent of the power to the rear wheels, but the car is also able to vary the torque sent to individual wheels, not only to provide traction but also to enhance cornering. Nineteen-inch wheels (235/35 front, 295/30 rear) are attached to a control-arm suspension. The ceramic disc brakes are electrically actuated and, naturally, have a regenerative function as well. Of course, the e-Tron also will need to be plugged in, and a full recharge takes 6 to 8 hours on a household current or 2.5 hours with a high-voltage (400w) charging station.

The e-Tron's other high-tech features include a heat pump for interior climate control, closeable air intakes (in the grille and along the sides of the car), an iPhone-like touch-screen scroll pad to control Audi's MMI interface, and intelligent, all-LED lighting that uses a forward-looking camera to vary the light pattern of the headlights in reaction to oncoming traffic (available now in the Mercedes E-class) and also takes clues from the nav system to turn on cornering lights as the car approaches a curve.

It all sounds good, but don't go rushing down to your Audi store just yet (or at least, don't go expecting to put your name on the list for a new e-Tron). As the company itself says, "There is still a lot of work to be done before electric cars are ready for volume production."

In other words, this e-Tron is not about to start stealing sales from the Tesla Roadster. Instead, Audi's battery-powered e-Tron concept is the high-visibility kick-off to a three-year project (for which the German Ministry of Education and Research is kicking in at least €10 million Euro) consolidating its research on electric mobility.

Audi e-Tron Concept

On sale: Not anytime soonPowertrain: 53 kW Lithium-ion battery, four electric motorsOutput: 313 hp, 3319 lb-ftTransmission: Direct driveDrive: 4-wheelBody style: 2-seat sports carCurb weight: 3527 lbsLength: 167.7 inWidth: 74.8 inHeight: 48.4 inTires/wheels: 235/35 front, 295/30 rear; 19-inch wheels