That loud sobbing and collective forehead slap you heard in late 2008 was the reaction of thousands of Audi fans and car nuts in general upon learning that the all-wheel-drive Audi S4 performance sedan would be losing its meaty V8 in favor of a supercharged V6. Several automotive scribes are known to have belted out a Homeresque "D'oh!" After all, V8 engines are the stuff of automotive legend, their guttural sound recorded and replayed as lullabies to the children of gearheads. What was Audi thinking?

Well, it turns out they knew what they were doing. The 2010 Audi S4 indeed tosses away its V8 for a 3.0-liter supercharged V6 that produces 333 horsepower and 325 pound-feet of torque; to save you the effort of looking it up, that's 7 fewer horses than the old 4.2-liter eight-cylinder but 23 more lb-ft of torque. The result is a car that's actually quicker than the one that disappeared two years ago when the A4 sedan upon which it was based was completely redesigned. But this stellar new engine is about more than just the numbers. The immediacy of the S4's throttle response is nothing short of amazing -- save for the moderate supercharger whine under hard acceleration, the blown V6 acts just like a naturally aspirated motor, albeit one with a boatload of low-end torque. Those who questioned Audi's cylinder-reduction strategy will be very pleasantly surprised.

The new S4 not only adds speed, but gets substantially better fuel economy as well. The 2010 S4 achieves a whopping 6 mpg (combined) more than the car it succeeds, including a surprising 27-28 mpg on the freeway. That's also better than the similarly swift BMW 335i, even though the rear-wheel-drive Bimmer weighs less and has a taller top gear. If this is the environmentally friendly future of performance driving, color us excited.

There's a lot more to the 2010 S4 than simply its engine, however, as the entire car is now better positioned to compete against other sport-tuned sedans. Like last year's fully redesigned A4, the S4 boasts fresh styling and electronics interfaces along with myriad mechanical improvements. Exclusive to the S4 is a new seven-speed dual-clutch automated manual for those who want the ease of an automatic but without the performance drop-off and lack of involvement that usually goes along with it. An optional sports rear differential is also new, helping to bring the S4's handling more in line with its RWD-platform rivals.

It's important to note that the S4 competes more against the BMW 335i than the razor's-edge M3 in terms of both price and performance. For maximum thrills, albeit at a higher cost, we'd suggest looking at the M3 as well as the Cadillac CTS-V and Mercedes C63 AMG. Also, if a coupe or convertible is more your thing, the Audi S5 is essentially a two-door S4 -- plus, the coupe still comes with the V8. Still, the 2010 Audi S4 is an undeniable winner. Those depressed car nuts should relax; the new S4 still has plenty of verve.

The 2010 Audi S4 is a high-performance sedan available with one of two packages: Premium Plus or Prestige. Standard equipment for the Premium Plus includes 18-inch wheels with summer tires, a sunroof, automatic xenon headlights, LED daytime running lights, foglights, automatic wipers, tri-zone automatic climate control, eight-way power sport seats, leather and faux-suede upholstery, heated front seats, a 60/40-split-folding rear seat, Bluetooth, a dash-mounted Multi Media Interface (MMI) electronics controller and a 10-speaker stereo with single-CD player, satellite radio and an auxiliary audio jack.

The S4 Prestige adds 19-inch wheels, auto-dimming interior and exterior mirrors, driver memory functions, keyless ignition/entry, voice controls, a 14-speaker Bang & Olufsen stereo, a next-generation MMI controller mounted on the center console and a hard-drive-based navigation system with real-time traffic.

The navigation system is optional for the Premium Plus package, as is the upgraded audio system. The available Audi Drive Select Package adds adaptive suspension dampers, an enhanced steering system, a sport rear differential and selectable driving settings. Stand-alone options include 19-inch wheels, adaptive cruise control, full leather seats and a power rear sunshade with manual rear side shades.

The 2010 Audi S4 is powered by a 3.0-liter supercharged V6 that produces 333 hp and 325 lb-ft of torque. Power is routed through Audi's ubiquitous Quattro all-wheel-drive system, which features a 40/60 front/rear torque split. A six-speed manual transmission is standard, while a seven-speed dual-clutch automated manual (S tronic) is optional. A sports rear differential (which varies torque between the rear wheels) is also available.

Audi estimates a sprint from zero to 60 mph will take 4.9 seconds. EPA-estimated fuel economy is above average for this class of car, with 18 mpg city/27 mpg highway and 21 mpg combined with the manual. The S tronic returns 1 mpg more on the highway.

The 2010 S4 comes standard with stability and traction control, antilock brakes, front side airbags, side curtain airbags and a hill-holder for the manual transmission. Rear side airbags are optional. Also optional is an "Active Braking Guard" feature that's part of the adaptive cruise control. If an imminent collision is detected, the system alerts the driver and primes the brakes for full stopping power.

Though the new S4 has not been crash tested as of this writing, the regular A4 received perfect five-star scores for both front and side impacts in government testing. Likewise, in Insurance Institute for Highway Safety crash tests, the A4 earned perfect ratings of "Good" in both frontal offset and side impact crash testing, and that was without the optional rear-seat airbags.

The 2010 Audi S4 is a sharp-handling car, with tenacious AWD traction and little body roll to speak of. Although it corners extraordinarily well, it still provides a reasonably comfortable ride. We'd skip the optional Audi Drive Select system, however, as it makes the driving experience overly complicated -- and the standard suspension, throttle and steering calibrations are just fine. The only downside to the S4's handling is its steering, which is all too typical of recent Audi products: artificial in feel with sometimes unpredictable weighting.

The new supercharged V6 doesn't yield the same knee-weakening auditory pleasure as the Audi S5's V8, but it sounds plenty spirited, and it boasts more torque and vastly better fuel economy. This is a smooth, strong engine with instantaneous throttle response. Aside from the subdued supercharger whine, you'd probably never guess there's forced induction going on under the hood.

The standard manual transmission shifts smoothly, though its clutch travel and shifter throws are a bit long. An excellent alternative is the dual-clutch automated manual transmission -- it snaps off rapid shifts either by itself or through your own inputs via wheel-mounted shifters. Even if you're a serious driver, there's no shame in ordering this automatic option.

The 2010 S4's cabin is one of the nicest in this class. The control layout is attractive, if rather button-happy, and the seats are both supportive and comfortable. Available two-tone color schemes add a bit of flair.

The MMI controls are conveniently arrayed around the console-mounted shifter on models equipped with the navigation system. However, the controls are mounted on the center stack in navigation-less S4s, and reaching forward to operate them is a hassle. This MMI is also an older design, with inferior graphics, more confusing menus and no joystick-like knob that makes certain inputs easier.

Other controls are at least generally intuitive and well laid out, though accessing certain features can be an exercise in frustration -- adjusting something as simple as the fan speed, for example, is a two-step process. Like the A4, the S4 features a roomy cabin that can accommodate four adults for an extended drive. Trunk space is listed at 12 cubic feet.