The Audi A4 has a stable, planted feel that's confidence-inspiring whether you're out on the open road or in urban congestion. It's not quite the dynamic rival of the Infiniti G37, Cadillac ATS or the BMW 3-Series, but it draws much closer to those handling heights when it's transformed into an S4.
The A4 sedan sports a single powertrain. With 211 horsepower and 258 pound-feet of max torque, the 2.0-liter turbocharged four-cylinder engine has a bit of lag under 2000 rpm before it hits the interesting stretch of its torque curve. Then it runs smack into a rush of boost and that torque comes on, all the way up to redline. The automatic eight-speed version can get to 60 mph in just 6.3 seconds; a manual version sits in the same range, while the version with the continuously variable transmission's pegged at 6.7 seconds. All are rated at a top speed of 130 mph. The numbers fall behind the latest from BMW and Cadillac by a half-second or more, but are in line with the likes of the Mercedes C Class.
The six-speed manual gearbox that comes standard on the A4 shifts with more BMW-like precision and less of that loose, notchy VW feeling than those in previous models. Audi's handy electronic parking brake engages with a quick lift-on or release-down motion, and automatically releases as soon as you lift the clutch to its friction point. Its taller ratios can affect drivability a little bit, requiring downshifting two or even three gears for passing, but they sure do help fuel economy. Available on quattro models is an eight-speed automatic that's smooth and never misses a beat.
There's also the CVT-equipped model, which we don't recommend in either front- or all-wheel-drive form unless you're shopping purely on cost. CVTs don't respond as quickly as a great automatic, and the A4 now has one of those with its updated gearbox.
The A4's steering system has been exchanged this year for an electric one that's an improvement in some ways. It helps fuel economy across the board, and allows a wide range of tuning for light-touch feel in base A4s and meaty feedback in versions with adaptive steering. On the A4 with the base suspension and 17-inch wheels, there's plenty of body roll and the steering requires lots of angle off-center to generate actual movement; in contrast it doesn't feel twitch or wandery like some EPS systems. All-wheel drive is now available, and for some climates, it may be an option you'll want, though it cuts fuel economy and adds even more weight to the hefty A4. That's an A4 really only meant for label fans and lease-deal shoppers.
Above and beyond the CVT-equipped models, the A4 earns more sport-sedan stripes. Quattro is standard with either the automatic or the manual, and on these versions there's a more assured feel that comes with stronger acceleration and an available Sport package. The Sport setup's ride comfort can be a little firm for some kinds of roads; the taut tuning of the sport suspension transmits lots of road surface through its 18-inch wheels and high-performance summer tires.
On its most expensive versions, the A4 can be fitted with variable-ratio Dynamic Steering and Drive Select, which tailors its electric power steering, transmission, throttle and shock settings for sporty or soft driving in Comfort, Auto, Dynamic, or Individual modes. Our past experiences with Drive Select have steered us away from it--it's difficult to find mutually agreeable settings between all systems, and it's an expensive option that's easy to pass up. Brakes remain one of our few nitpicks with the A4. Over a couple of manual-transmission test cars they've felt overboosted and grabby at low speeds, though strong and confident for higher-speed use.
The S4 ups all the dynamics of the A4, mostly to excellent effect. The four-cylinder turbo gives way to Audi's 3.0-liter, direct-injected and supercharged V-6, good for 333 horsepower. Audi pegs its 0-60 mph times at 4.9 seconds, and top speed rises to 155 mph; engine noise isn't as sweet as the former V-8s, but sharp throttle response is. The S4 offers the manual transmission, but Audi's magnificent dual-clutch seven-speed transmission is available. It's our pick--shifts are exceptionally quick and the ratios are tightly chosen. Some city driving will feel less smooth because of the dual-clutch's inherent shortcomings in that scenario, but the S4 gets into a groove in sweeping curves and tight corners, where paddle shifters and the millisecond-swift shifts encourage dancing around the gears.
Like the A4, the S4 adopts electric steering, cutting weight on the front end and boosting the dynamic range of the steering even before variable-ratio Dynamic Steering and Drive Select control are added. The S4 also offers an active sport differential to go with its standard all-wheel drive; the combination of the rear-biased (40:60) quattro system and the differential's power-splitting between the rear wheels gives it a more planted feel, awesome road-holding potential and great, grippy feel. It's entertaining to press to its tire limits, but on previous tests, we've found the Drive Select system dials in lots of artificial heft to the electronic power steering. There's some usable flexibility built into the system, in terms of ride comfort and transmission response, but for the most part, Audi's base configuration works well enough to avoid the expensive option.