Strap into the sleek Audi A6 4.2, and you'll enjoy the heady thrust of 350 horsepower. Or perhaps the BMW 550i's mighty 360 ponies are more to your liking. You also could strut about town in a Mercedes-Benz E550, boasting to all within earshot of your ride's thunderous 382 horsepower.
On the other hand, maybe you're one of those defiant souls for whom such lofty power ratings elicit a different response: "Not enough."
Ah, then please follow us down the hall. First we need to run you through Paycheck Analysis (good, good-you've got the requisite digits in your bank account) followed by a quick screening in Velocity Tolerance (check your preconceptions at the security desk, please). Thumbs up? Splendid. Now, be patient a moment longer while the guard deactivates the Laser Drool Neutralizer and...feast your eyes on those! You're looking at the three latest supersedans from Germany's leading premium brands. What's that? They seem tame? Why, that's the whole idea. These babies may pattern their sheetmetal after their conventional A6, 5 Series, and E-Class counterparts, but underneath they're Terminators.
You already know about the M5, which BMW launched in all-new, fourth-generation form for the 2006 model year. Let's not pass up a chance to review the car's high-adrenaline vitals, though: world's first V-10 engine in a production sedan; 100 horsepower per liter of displacement (that's 500 horses in total); 8250-rpm redline; seven-speed sequential-manual paddle-shift gearbox (or, for 2007, optional six-speed manual); cross-drilled, ventilated disc brakes; M Dynamic Mode for the ultimate in computer-aided, dancing-on-the-limit handling; and...hey, should we turn the Drool Neutralizer back on? In the M5's first title fight, against the Mercedes-Benz CLS55 AMG (March 2006), the beastly Bimmer won a close decision, its fighter-jet responsiveness edging out the Benz's headbanging straight-line thrust.
Since then, however, two new, exceptionally worthy rivals have emerged from Deutschland. Audi's latest weapon is the new S6 sedan, third generation of a model first introduced in 1995. Like the M5, the S6 brandishes V-10 power, in this case a 5.2-liter version of the engine Audi also builds for corporate colleague Lamborghini (where it serves in the Gallardo sports car). For S6 duty, the 40-valve, aluminum V-10 is detuned slightly, producing "only" 435 horsepower at 6800 rpm, but it's still very much an "exotic" powerplant: direct injection, magnesium variable intake manifold fed by two separate air paths (each with its own air filter), hydraulically adjusted, chain-driven double-overhead camshafts. The engine distributes the considerable fruits of its labors to the road through a standard six-speed automatic with Tiptronic and quattro permanent all-wheel drive. The only visual giveaway is a "V10" badge on each side.