The drops the 4.2-liter V8 for a 3.0 supercharged V6 with less power and a strange "T" badge. Is that the recipe for a sport sedan finally capable of besting arch-rival BMW and making our 2010 Best10?

That "old" 4.2-liter V8 produced 340 HP and is still used in nearly every car Audi makes, from the platform-sharing 2010 Audi S5 to the Audi R8 4.2. It's an amazing engine in all its forms, combining V8 sound with instantaneous revs. Hopping in the S4 for the first time, I was pretty disappointed by its absence, the new direct-injected and supercharged V6's drone would sound right at home in a Camry and there's no audible sign of the supercharger whatsoever.

But that humdrum new sound and the "V6T" badges are masking what's actually an exceptional engine. Power is down 7 HP to 333, but torque is up by 23 Lb-Ft to 325, with the peak now arriving 900 RPM earlier and spreading across a plateau from 2,900 to 5,300 RPM. The effect of that is predictably much more low down shove for everyday driving, but, unpredictably, fuel economy gets a huge boost from 13/20 (city/highway) on the V8 to 18/27 MPG for this manual six speed.

The new S4 is also cheaper, with the base version starting at just $45,900, $2,710 cheaper than the old V8 and without the $1,700 gas guzzler tax on top of that price tag.

But that's only the beginning. The 2010 S4 also comes with an optional $1,100 torque-vectoring rear differential that works with the 40:60 front to rear power split and stability control to all but completely eliminate understeer. An Audi without understeer? This is starting to get interesting.

The S4 starts with the new Audi A4's well-proportioned, classy exterior and manages to add both aggression and fanciness without making the car look tacky. "S" additions include LED rear lighting, a more aggressive front grille with egg-crate silver slats, an integrated rear spoiler, aluminum mirror skins, 18" wheels, "S4" branded calipers, a grey rear diffuser with an aluminum bar and four aluminum exhaust pipes.

It's small, it's got four doors, it doesn't need huge wheels to fill the arches (these are 18 inches), it's sexy, it's understated and it looks far more expensive than its sticker price. What's not to like?

Like the exterior, the interior has a very solid base to work with, making smart additions to ritz things up: brushed aluminum trim; subtle "S4" logos on the steering wheel, door sills, the key fob and the gauges; high-backed and heavily bolstered sports buckets out of the S5. Sat/Nav is optional.

Also like the exterior, the interior is so nicely appointed, classy-looking and well laid out it makes you feel like you're driving a far more expensive vehicle. We give the S4's interior the nod over the questionable materials and less well-resolved layout in the A6.

Rear knee room is increased an inch and a half over the old S4, which means you can fit two full-size adults back there in comfort.

Bear in mind that this is a $45,000 rival for the 335i, not an M3 beater. 0-60 takes just 4.9 seconds (down from 5.3 in the V8) and top speed is restricted to 155 MPH. This dyno chart gives you an excellent idea what the engine feels like, there's that big fat torque curve starting at low RPMs, then the significant power peak on top.

People like to say that the 335i's twin-turbo inline six gives the M3 a run for its money with 300 HP and 300 Lb-Ft of torque, yet this Audi makes 333 HP and 325 Lb-Ft, making up for the extra 253 Lbs it's packing over the 2WD Bimmer.

Gear ratios are fairly short, with only a 2,000 RPM difference between first and third gear at 20 MPH. Combine that with the instantaneous throttle response and all that torque and you have an engine that's immediately responds to anything you ask of it.

Since Audi cut the 3.2-liter V6 from the lineup, the S4 is now the upgrade model from the A4 2.0T. This was Porsche 911-level performance early last decade, it's hard to believe that's now available on the second tier of a compact sports sedan.

The only negative is the lack of character we touched on earlier. The TFSI V6 drones in an utterly uninspiring manner. It might not sound as good as the V8, but more torque, considerably improved fuel economy and a lower cost makes up for the lack of an appealing engine note.

I really need to write an article on torque vectoring differentials. In short, they work kind of like stability control in tweaking individual wheels to keep things in line. Unlike stability control, torque vectoring does that by applying power, not brakes, so it speeds you up instead of slowing you down. The S4 uses a torque vectoring differential on the rear axle, which then works in conjunction with the stability control to eliminate understeer. Really. By moving power to whichever rear wheel has the most traction, it also makes sliding the rear end around a breeze, working to keep things pointed sideways rather than backwards as long as you're on the power. Driving the S4 in the snow on snow tires is a hoot, there's absolutely no need for any electronic nannies to be switched on, with the car behaving more like the predictable narrow-tired RWD sedans of yore than modern rivals that have lots of grip, but no ability to be put through a controlled slide.

In less slippery conditions, the S4 is proved to be an equally capable performer, but does still suffer from a hint of Audi's trademark lack of steering feel. Thankfully, this model wasn't equipped with the silly Drive Select system, which makes things worse by buggering up the steering with artificial weight instead of feel. Other than that reservation, the chassis complements the responsive, powerful engine with agility and quick steering.

Slowing things down, there's little penalty to comfort from the S4's increased performance. It helps that the 18" wheels don't wear super low profile tires, but the suspension somehow manages to be both firm for handling, yet controlled for ride. Over my usual BQE ride torture test, I couldn't detect a remarkable difference between the A4 and S4's ride.

It's a spec'd up Audi, so mastery of toys and tech is to be expected. This would be my choice of spec too, dropping the horrible Drive Select, but including MMI, Sat/Nav and a third pedal. The Sat/Nav is easy to use without taking your eyes from the road, slick-looking and full of info. Even I was able to connect my iPhone to the car via Bluetooth and you can fully integrate your iPhone or iPod control into the MMI system and listen to Pandora on the go. There's two SD slots, keyless entry and starting, voice control and a 505w Bang & Olufsen stereo. You won't get bored in a traffic jam if you're driving an S4 — however you may be befuddled by the control interface.

The S4 feels like an incredibly special car. It's faster, better looking and more fun to drive than the $40,600 (stripped) 335i; all those things and more luxurious than the $39,750 Mercedes C350; all those things and better looking than the $45,725 Cadillac CTS 3.6. In fact, it offers most of the performance and fun of cars like the $55,400 BMW M3 and $57,350 Mercedes C63 AMG, for only $45, 900. That's amazing value to us. We only wish it sounded as exciting as it was to drive.

Our pick of the entire Audi range (well, except for the R8 supercar), the S4 makes other sports sedans look silly with its appealing looks, swanky interior and sheer speed, then adds a tangible technological benefit in the form of torque vectoring. Relatively small, well-packaged, classy-looking, high performance four-doors used to be the sole preserve of another German automaker, but while they've been focussing on making bloated SUVs for housewives in New Jersey, Audi has made the S4 one of the ultimate driving machines.

Now, for the vitals and who should and shouldn't buy the 2010 S4...

● Speed Merchants

● Euro Trash

● Technogeeks

● Bimmerphiles

● Tuner Crowd

● Working Stiffs

● SUV enthusiasts

● BMW 335i: slower, less fun, ugly.

● Cadillac CTS 3.6: slower, less fun, more American.

● Mercedes C350: slower, less fun, less luxurious, weird looking.

● BMW M3: a much better performance car, but most drivers would be better off in an S4 day-to-day.

Model Year: 2010

Make: Audi


Model: S4


Trim: Premium Plus


Price, Base/As-Tested: $45,900/$51,475

Engine: 3.0-liter direct injected, intercooled, supercharged V6

Horsepower & Torque: 333 HP @ 5,500 RPM, 325 Lb-Ft @ 2,900 RPM


Transmission: 6-speed manual


Curb Weight: 3,850 Lbs
0-to-60: 4.9 secs (manufacturer quoted)


Top Speed: 155 MPH (limited)


Crash Testing, Front/Rear/Side: *****/*****/*****


Fuel Economy, EPA: 18/27 MPG