Audi's 4.0 L Powertrain With Quattro
Propelling the A8L from 0-60 in a mere 4.2-seconds (according to Motor Trend's tests) is a 4.0 L V8 engine rated for 420 hp. It makes 444 lb-ft of torque at a very low 1500 RPM and sends the nearly two-ton A8L down the quarter-mile in 12.6 seconds. That's sports car-fast in a limousine form factor. The four-liter motor with overhead cams, variable valve timing, and a pair of twin-scroll turbochargers increases power while maintaining efficiency.
Speaking of efficiency, this configuration receives an EPA rating of 16/26 MPG in city and highway driving. That might seem low compared to a hybrid, but my wife’s minivan gets close to the same mileage with 134 fewer horses and much lower performance stats. So long as you stick to highway cruising, this land barge will reward you with respectable fuel consumption.
Audi mates the 4.0 L V8 to a very familiar ZF 8HP eight-speed automatic transmission, which is used in pretty much everything from Jeep's Grand Cherokee to Jaguar's F-Type, which are both vehicles we’ve reviewed. The A8L's ZF 8HP is no different. It delivers quick and smooth shifts, though it's not as snappy as the F-Type. Power is then sent to all four wheels through Audi’s Quattro all-wheel drive system. By default, the power split is 40/60, with a bias to the rear wheels.
Naturally, the A8L's powertrain makes it more of a joy to drive than if the car were underpowered. The four-liter engine is great for merging into traffic or overtaking on a two-lane road. Fuel efficiency suffers, of course, if you can't keep that tendency under control. But something tells me that anyone dropping six figures on an executive cruiser isn't sweating the price of oil. Quattro keeps the A8L planted around corners, while the rear bias helps prevent understeer. Although the car weighs almost two tons, the A8L is still a lot of fun to drive.