The TL's willingness to rev (and stall) no doubt comes from the particulars of its V-6. Like most cars based on a front-wheel-drive design, the Acura's engine is installed transversely, and a narrow engine helps maximize both frontal crush space and interior room. To that end, Acura uses a 60-degree angle between cylinder banks. This layout is well-balanced as far as V-6s go and negates the need for balance shafts. Despite its size (a robust 3.7 liters of displacement), it revs instantaneously, and the only drawback to the low rotational inertia is slightly gritty power delivery. That's a nonissue in the TL, since any coarseness is overshadowed by magnificent intake music, especially as the valvetrain switches over to the high-lift cam profiles at the fun end of the tach. It pulls hard to its 6700-rpm redline, and the harder you drive the TL, the better this powertrain becomes.
You won't hear a single complaint from us about the Audi's driveline. Except that if "Acura TL SH-AWD 6MT" is a stupid name for a car, then "3.0T" is a stupid badge to put on a supercharged engine. Unless, of course, the device is called a Tupercharger in German. Which it's not. Mounted longitudinally, the 3.0-liter V-6's banks are splayed out at a 90-degree angle, and thanks to balance shafts and counterweights, it's as smooth as silk. It's also decidedly more high-tech than the Acura's engine, with four cams instead of two, direct injection, and of course, the silent tupercharger that you never hear but, oh, my word, do you ever feel. The power-to-weight ratios may be similar, but the S4 is a full league quicker and faster than the TL thanks to the additional torque across the entire rev range.
The Audi's extra thrust should have been a huge advantage at Pittsburgh's BeaveRun racetrack, which rewards straight-line speed with two long straightaways -- especially since, on paper, the Acura carries no advantage in cornering or braking: the two cars have similar weight, tire section width, and suspension designs. The Audi's slightly better weight distribution would, we thought, be nixed by the Acura's wider track. And we were right -- as expected, the cars posted similar braking and cornering numbers in standardized testing.
But on a racetrack, the TL showed us exactly why Acura used the word "super" to describe its Super-Handling All-Wheel-Drive system. Despite its significant power advantage, the Audi S4's fastest lap beat the TL's by only 0.4 second.
Although the two all-wheel-drive systems are different in design, they both strive to accomplish the same thing: temporarily routing extra power to the outside rear wheel to help rotate the car in a turn. The big difference here is how these two cars are set up to handle to begin with.