The Audi e-tron is classically proportioned as a midengine supercar, but its razor-edged detailing speaks to the unconventional technology underneath. The LED headlight arrays are highly variable.
The Audi e-tron might look like a run-of-the-mill, high-performance sports car, but don't let appearances fool you. This all-electric prototype isn't just four wheels and an accelerator. Audi made extensive use of aluminum and carbon fiber in building the car — which is based on the German carmaker's vaunted midengine R8 supercar — and made the doors, roof and other body panels of fiber-reinforced plastic. Driver inputs are all space-age: the rearview mirrors have been replaced with closed-circuit television monitors, and the propulsion system is state-of-the-art electric. This car is truly a look into the future of the automobile, and is completely dedicated to showing off the automaker's prowess in the high-tech arena.
But for all its gee-whiz gadgetry, high-tech engineering and forward-thinking design, the most amazing thing about this car is that it's as close to a production model as a prototype gets. In fact, Audi says it will build 100 e-trons in 2012, with more to come if demand warrants. If Audi can deliver on this promise, it would be like your power company pledging to build lunch-box-size nuclear reactors that will power your house for pennies a month, then actually doing it within a couple of years.
We were recently given a chance to drive the e-tron — under tightly controlled conditions, of course. Don't forget it is a concept car, designed to whet our appetites for electric propulsion in general and to buff Audi's logo in particular — it's not ready for prime-time production. Even so, the experience was an eye-opener.
Nuts and Bolts
Only two e-trons currently exist. They both use slightly smaller, modified versions of the aluminum spaceframe from the Audi R8. Other than that, the e-tron is essentially all new from the ground up.
The svelte carbon-fiber bodywork is very much show-car stuff. There is no "hood" for the "engine compartment," no trunk lid and no trunk. Those will all come in the production version, but for now the e-tron's facade is young and taut, free of cut-lines and styling blemishes.
Under all that sleekness hides the heart of this lean and mean-looking beauty: an electric motor at each wheel, a 100-cell lithium-ion battery pack and a water-cooled power-control unit. Computers from existing production Audis (with a software upgrade, of course) are used to shuttle electrical power among the four motors for the ultimate in quattro technology. The automaker calls it "force vectoring," but by any name it allows easy control over mundane issues such as traction control in slippery weather, and unparalleled ability to vary power for the ultimate in stability control.
View: More Pictures of the Audi e-tron
For instance, to counteract oversteer when exiting tight corners, the outside rear wheel can receive more power than its inside counterpart. Under normal conditions, power is shunted 70 percent to the rear wheels to mimic traditional sports-car handling. This is in concert with the e-tron's "midengine" weight distribution, thanks to the battery pack location immediately behind the cockpit.
This ability to seamlessly vector thrust among the four tires is a fundamental advantage to the all-electric powertrain. Similar control has been attempted many times before — Audi does as much currently with its conventional powertrains — but the lag and lash of mechanical systems can't compete with the smoothness and speed of electric control.
Furthermore, the four-motor drive allows equally flexible control during braking, or braking for stability control. And unlike conventional brakes, energy is recouped to the batteries rather than discharged as waste heat. That said, the e-tron is fitted with massive, 4-wheel discs strictly as show-circuit window dressing. Conventional brakes are still required, but they can be much smaller and lighter because the motors handle most deceleration chores. Additionally, the rear brakes are electronically actuated — "brake-by-wire." Audi says this ensures no residual drag when not braking.
What do you think about the Audi e-tron?
In addition, many traditional systems you'd find in a typical automobile are missing in this set-up. There is no transmission; no engine air inlet; and no fuel tank, pumps or lines. There remains, however, a rather significant cooling system to keep the hot-running power controller cooled. It requires a conventional radiator and a front air grille.
A heat pump is also used to stabilize cockpit, controller and battery temperatures, because the electronics in this car have a relatively narrow efficiency range. As a result, the car is "pre-conditioned" whenever the e-tron is plugged into a charging station; i.e., the car is always either being cooled or warmed automatically to keep the temperature in the car consistent.
