When Audi’s Quattro all-wheel drive was in its infancy, erstwhile development chief Ferdinand Piëch—now head of Volkswagen AG's supervisory board, and perhaps the closest the auto industry has to a rock star—once said that the system should cost no more than a set of winter tires. That target might still be a way off, but Quattro’s handling merits are undisputed.
Not content with their current system, though, Audi engineers have recently given thought to the "Quattro drive of the future." The result is this A5-based e-tron Quattro concept, a plug-in hybrid with a four-cylinder gasoline engine and two electric motors. Up front is VW’s familiar 211-hp, turbocharged, 2.0-liter four-cylinder, making its usual 258 lb-ft of torque. Just behind it is a 45-hp, 156-lb-ft electric motor. Both send their power to the front wheels through a four-speed automatic transmission. (Yes, a four-speed. Audi wouldn’t say why.) There is another electric motor on the rear axle, this one making 81 hp and 236 lb-ft, which provides the car with all-wheel drive.
The Silent A5
Below 62 mph, the electric motors can power the A5 without any help from the gasoline engine. Combined, their peak output is 110 hp. If you need more, the gas engine fires up, and combined system power is 314 hp—almost on par with the S5 cabrio’s 333-hp supercharged V-6. Take your foot off the gas, and the electric motor at the rear recharges the batteries, which live in the center tunnel. The pack’s total capacity is 9.4 kWh. During deceleration, the system varies how aggressively it harvests energy from each rear wheel in order to maintain stability.
Thanks to extensive use of carbon fiber and aluminum, Audi managed to keep the weight of this concept around 3500 pounds, or barely above what a Euro-spec A5 V-6 weighs. But it's way beefier than the 2.0-liter lightweight concept we drove last year, which tipped the scales at just 2888 pounds.
Audi is seriously pursuing this vision of all-wheel drive, but says we won’t see any production payoff until 2014 at the very earliest. It isn’t the first company to flirt with the idea of all-wheel drive through electric motors—the Lexus RX450h has been doing it for years, and the upcoming Porsche 918 Spyder will drive its rear wheels with a gas V-8 and one electric motor while employing another motor on the front axle. But the A5 e-tron is heavy, and batteries and electric motors are expensive. If this is the future of Quattro, whatever happened to matching the cost of winter tires?
by caranddriver.com
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