I'm sitting in the left lane of a drag strip in a 2013 Audi S8, waiting for the staging light to go green. In the right lane is my opponent, a BMW M5, the "E60" model that ruled the supersedan world until 2010, its last year of production. When that M5 was introduced in 2005, there weren't enough superlatives to describe the awesomeness of its engine, a 500-horsepower, 5.0-liter V-10 with a redline beyond 8,000 rpm. That strapping V-10 seemed like a zenith of human engineering achievement, right up there with the SR-71 Blackbird and the TV remote. And yet, when this light turns green, I'll win the race. The reason is evident to anyone who can decipher the modest badge on the Audi's front fenders: V8T. Where T stands for turbo.

Just a few years ago, our favorite German high-speed sedans – the top-of-the-food-chain Mercedes-AMG models, the BMW M's, and Audi S-cars – were all about big motors and high revs. Mercedes had its monster 6.2-liter V-8, while Audi and BMW built beautiful-sounding V-10s. Well, things change in a hurry. As the great Fletch might have said, it's turbochargers nowadays.

In a sudden spate of tech homogeneity, our marquee German uber-four-doors now pack downsized twin-turbo V-8s. There is a social and environmental rationale here – fuel economy has generally improved compared to the old motors – but the sneaky fact is that turbos allow these compact V-8s to crank out ludicrous horsepower. While the new S8 gets four miles per gallon better fuel economy than the old V-10 model, I'd say the rationale behind the change is 10 percent about mileage, 90 percent about hauling ass. When you're dropping $110,000 on a car, you're probably not sweating the economic hardship of that 15-mpg city rating.

Especially when paired with all-wheel drive, the turbo V-8 enables a huge luxury sedan to launch like a Vette while coddling with a Bang & Olufsen system, air-conditioned massage seats, and power-window sunscreens. These are everyday, carpool-ready four-doors that won't attract undue attention from the cops or deform your spine on every highway expansion joint.

Compared to the old M5's deified V-10, the new M5's motor is a shrimp, with two fewer cylinders and only 4.4 liters. Yet the new car is rated at 560 horsepower, and that's a number it would hit when it's hungover and running on seven cylinders. Doing a burnout is one thing; doing a burnout the length of a football field on dry pavement is another.

Also challenging its traction-control system is the Mercedes-Benz E63 AMG, now armed with a 550-horsepower, 5.5-liter V-8 that cranks out a ridiculous 590 lb-ft of torque. While you had to rev the hell out of the old 6.2-liter to get the power boiling, the new turbo V-8 seems to reach full thrust the moment you twitch your right foot. I drove that car in L.A., where the steep canyons and brutal acceleration occasionally made me feel like an amateur astronaut on takeoff.

Adding to the entertainment, that particular E63 was a station wagon – not a grocery-getter so much as a grocery-­annihilator. Please ensure that your eggs and bags of Alpo are securely bolted down before you light off on a 4.2-second, 0–60 run. That stat, incidentally, applies to the 2013 edition of Mercedes' E63 wagon. Next year's car will be significantly quicker thanks to Mercedes' acknowledgment of what Audi already knows: These cars need all-wheel drive. Once the exclusive domain of foul-weather machines like Subarus, all-wheel drive is becoming a necessity for performance cars – especially ones with violently turbocharged V-8s. When you're flirting with 600 horsepower, two-wheel drive just isn't enough.

The S8, then, represents the current best practice for German muscle sedans: turbo V-8 plus all-wheel drive. The result, I must say, is pretty spectacular. While the owner of the V-10 M5 fiddles with tire pressure and launch rpm to extract his quickest run at the drag strip, I simply put the Audi in drive and stomp on the gas. We race four or five times. The S8 never loses. It's a little like watching a once-feared boxer lose to an upstart. You almost feel bad for the champ.

In fact, it runs an 11.7-second quarter mile at 117 mph. For perspective, that means this hulking Audi – which weighs as much as a Range Rover – delivers acceleration in the same league as cars like the Corvette Z06 or Nissan GT-R. Which brings me to another point about German turbocharged motors: Their power ratings tend to be conservative. Why? I don't know, but the Germans evidently delight in downplaying their horsepower, thus making it seem as if their improbably quick cars are imbued with dark Teutonic magic. If there's a drawback to the S8's stupendous capabilities, it's that perhaps they come a little too easy. The guy in the previous-generation M5 is feathering the gas pedal, watching the tachometer, listening to the howl of that V-10 to know when to upshift. He's driving. And when we're alongside, hurtling down that drag strip, I can actually hear the wail of that BMW above the muffled rumble of the S8. My car is faster, but his is more visceral.

The new M5, with its ferocious turbo V-8, is absolutely diabolical with the traction control disengaged. It's a tail-happy, tire-smoking runaway rhino on steroids. It really needs all-wheel drive. But I'm a little bit glad that it still doesn't have it.