Audi S4 and S5 Cabriolet (first drive)

We were recently handed the keys to a fully loaded, brand-new Audi S4 sedan. We 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.

We like that the S4 looks sportier than its milder sibling, the A4, but not wildly so--like the BMW M3. All visual upgrades are subtle and understated.

For 2010, Audi has dropped the previous S4's big V8 in favor of a supercharged 3.0-liter V6. Although down two cylinders, the direct injected V6 manages to output 333 horsepower and 325 pound-feet of torque.

The S4 hits 60 mph from a stop in 4.9 seconds before continuing on to its top speed of 155 mph. Compared with the already strong acceleration of the 3.2-liter V6 A4 we tested earlier, the smaller displacement, higher powered S4 is a revelation.

The S4's braking system has received upgrades to match the overall performance of the vehicle.

Meanwhile, Audi Drive Select gives drivers control over the the vehicle's suspension tuning, steering rates, power and throttle response, transmission shift points, and rear differential configuration.

The S4 features aluminum finished side view mirrors that house low profile turn indicators and LED indicators for the blind-spot-monitoring system.

Out back, the S4 features an aluminum finished diffuser and quad exhaust tips, which echo the standard Quattro all-wheel drive.

The S4's Quattro all-wheel-drive system is tuned for performance with a 40/60 normal rear bias for more a more sporting feel.

New for 2010, the S4 (and S5 Cabriolet) receive Audi's upgraded active rear differential. This new system utilizes torque vectoring to actively send power to the outside rear wheel during cornering to minimize understeer and to help rotate the vehicle through the turn.

Using Audi Drive Select, we were able to selectively activate and deactivate the rear differential's torque vectoring system for track testing. We found that the system does a remarkable job of tuning out understeer. At it's most dynamic setting, we were even able to get a bit of tail-out action, thanks, in part, to the additional power.

On the road, we found the 3.0-liter turbocharged V6 to be more than adequate for rocketing out of corners.

Our model was also equipped with Audi's seven-speed S-Tronic double-clutch automated manual, which allowed for lightning quick upshifts and buttery smooth downshifts. We almost prefer this system over the six-speed manual for its versatility.

Inside the S4's cabin, we were treated to grippy leather bucket seats and high-quality materials, such as real aluminum trim.

We've already tested Audi's new MMI in the 2009 Q5 and we mostly loved the improvements it brings in functionality, but still think the quadrant-based control scheme has a bit of a steep learning curve.

The hard-drive-based navigation system is powered by Nvidia graphics, which results in crisp visuals on the map screen. 3D building data for major cities adds a bit of eye candy, but is also useful for users who navigate better with landmarks and visual cues. Traffic flow data is displayed as a color overlay on the mapped roads.

Also on hand was the Audi S5 Cabriolet, which takes the A5 coupe's sexy proportions and chops the top.

Despite being a drop top, the S5 retains a 50/50 folding rear seat with pass through to the trunk, which is very useful for carrying long objects such as skis. Very cool.

The Audi S5 Cabrio features a power retractable soft top. Audi assures us that the canvas top is just a quiet as the fixed roof variant at highway speeds thanks to gratuitous sound deadening.

Unlike most long, four-seat convertibles, the S4 doesn't look unwieldy or oddly proportioned with the roof raised. Still, she looks much better with the top down.

To keep wind noise at a minimum, the S5 Cabrio can be equipped with this rear windscreen, which also blocks off the rear seats. Behind the rear headrests, we can see the doors for the pop-up roll bars, which deploy in the event of rollover.

Like the S4, the S5 Cabriolet features Audi's new 3.0-liter supercharged, direct injected V-6, standard Quattro with 40/60 rear bias, and torque vectoring active rear differential.

In fact, the S5 actually has more in common beneath the sheetmetal and on the road with the S4 than it does with the A5, on which it is based.