I was recently handed the keys to a fully loaded, brand-new Audi S4 sedan. So, I did what any motorhead would do in this situation and proceeded to put the sporty A4 variant through its paces on the open road, on an autocross cone course, and even on the track at Infineon Raceway at Sears Point.
Our adventure starts with a trip from an uncharacteristically sunny San Francisco across the Golden Gate Bridge and into Sonoma. While in the stop-and-go bustle of the city, the S-Tronic DSG double-clutch automated manual was so docile and the 3.0-liter supercharged V-6 engine so even tempered, that I almost forgot that the S4 was the performance variant of the A4 sedan line. This is mostly due to Audi's Drive Select system, which gave me limited control over the suspension tuning, power delivery, and steering ratios, effectively making the S4 two cars in one: a comfortable boulevard cruiser and a rip-snorting canyon carver.
All systems set to comfort, I was able to focus on the third-generation MMI and it's absolutely beautiful Nvidia graphics. The hard-drive-based system featured traffic data map overlays, 3D building data, text-to-speech turn by turn directions and voice control. The system also integrates into the audiophile quality Bang & Olufsen audio system by allocating space on the hard drive for music storage. We've already seen this setup before in the recently reviewed 2009 Audi Q5, so be sure to check out that review for more info.
Even set up for comfort, the S4 quickly eats up the miles, and before I knew it I was at the raceway, ready to legally test the S4's limits.
The first test was an autocross-style, parking lot cone course, where I was able to test one of the newest additions to Audi's drive-train tech package, the active rear differential with torque vectoring. This new differential works with the S4's sport-tuned (40/60 rear bias) Quattro all-wheel drive system but actively sending power to the outside rear wheel during cornering to rotate the chassis through the turn, eliminating understeer.
Audi's Drive Select system allowed me to test the system with and without torque vectoring active for back-to-back comparison. On my first run, I found the S4 to handle neutrally, the Quattro system doing a good job of finding grip between its four corners. However, when pushed, the sedan defaulted to safe, predictable understeer. My second run, with torque vectoring active, allowed me to feel the rear axle step out a bit when pushed hard through a turn. This didn't translate into epic power slides or snap oversteer, but without fear of understeer, I was able to turn on the power much earlier and more predictably for faster lap times and, of course, more grins per lap.
The next portion of my S4 shakedown was a series of hot laps on the track. All systems set to their most dynamic, I donned my helmet and strapped myself in. Accelerating out of pit row, my first impressions of the V-6, DSG combination were pleasant. While the DSG was smooth and comfortable on the road, at the track, the transmission fired off lightning-quick upshifts, while the all-wheel-drive system made sure that as many of the 333 horsepower met the road as possible.
Tossing the S4 into the first corner, I was met with... understeer. Oh, crap! Lifting off of the throttle and allowing the Quattro system to reassert control over the chassis, I was reminded that the torque vectoring and all-wheel drive are not magic bullets that fix poor driving. However, as we navigated the next few corners with considerably more poise, I was surprised at how much control the active rear differential gives me over the attitude of the vehicle. It's almost as though the S4 behaves more like an RWD vehicle when you're in control, but reverts to AWD control when you run out of talent.
While the S4 makes short work of Infineon's short configuration, I'm hard pressed to call it a track car. The S4 just doesn't feel as comfortable on the track as it does on a twisty back road. While the new power train setup really make the S4 more capable than, say, the Audi A4 3.2 Quattro that we've recently tested, I can't help but feel that the sedan's limits are a little low to be taken seriously on the track. However, it's torquey power delivery and idiot-proof handling are exactly the sort of traits I look for in a good street car.
Prior to setting out, Audi informed me that the S4 was gunning specifically for the BMW 335i and the Mercedes C350, and that I should be keeping those vehicles in mind as I evaluated their sedan. With that in mind, I think I'd prefer the less powerful 335i for the track (with the manual transmission), but the car I'd want to drive home would definitely be the Audi.
When I'd completed my track session with the S4, I was tossed the keys to a 525-horsepower Audi R8 V10, but you'll have to wait until tomorrow to hear about that beast. Stay tuned!