Audi E-Tron is New Product From AUDI

Although it shares elements of its aluminum architecture with the R8, the E-tron is smaller, almost as short as an A3. Despite the generous wheelbase (102 inches), the cabin isn't particularly spacious.

The towering battery stack behind the rear firewall takes up even more space than the R8's V-10 engine, transaxle, and fuel tank combined. Wrapped in liquid-cooled safety foil, the lithium-ion cells provide an energy capacity of 53 kWh, an exact match to the Tesla. To extend battery life, only 80 percent of that capacity is used. The batteries power four electric motors, rated at a total of 313 hp. The whopping maximum torque of 3319 lb-ft needs to be scaled back drastically so that full acceleration doesn't peel the tread off the tires. "The biggest challenge is of course to synchronize the four motors," says Thomas Kräuter, technical project leader for concept cars. "Since each wheel can be accelerated and decelerated individually, this is no mean feat."