Hunger for more power and torque is insatiable, despite ever-increasing traffic densities and speed restrictions around the world. At least, that's the message relayed by the German auto industry, which continues to up the ante at a breathtaking pace. Just look at the 469-hp Mercedes-Benz CLS55 AMG and the 500-hp BMW M6-which are themselves merely starting points for more developments in this insane race. In the next two years, BMW will introduce a lightweight M6 CSL with about 550 hp and an even more powerful M6 GTR track special. Over at AMG, look for a 503-hp CLS63 AMG and a positively steroidal, 621-hp CLS65 AMG.
There is certainly no shortage of polarizing extremes between the CLS55 AMG and the M6: manu-matic or sequential-manual transmission; high torque or high revs; optimized ride or maximum grip; perfect balance or ultimate involvement; pragmatic beauty or focused fashion; and, of course, supercharged V-8 or normally aspirated V-10. In a way, these approaches sum up the divergent paths that BMW's M Division and Mercedes-Benz's AMG in-house tuner have always taken. These cars aren't as extreme as the AMG Hammer and the race-tuned E30-series BMW M3, but one is a tuned production car, the other more like a detuned racer.
Both cars look terrific. BMW's Chris Bangle has given the M6 its share of flaming surfaces, the nostrils of a race car, and a trunk lid reminiscent of an aircraft carrier's launch pad. Very moderne. M-B's Peter Pfeiffer created a wow-effect crossbreed of a coupe and a sedan, suitably beefed up with aerodynamic add-ons for the AMG version.
On the winding mountain roads of the Austrian Tyrol region, it's all too easy to dismiss the top-of-the-line CLS. Compared with the tied-down and precise M6, the laissez-faire Mercedes feels as if it were shod with winter tires. Even with the air suspension locked in the firmest setting, there is an occasional waterbed wobbliness when pushed. But on the entertainment scale, the arc-shaped four-seater easily matches its rival for lurid drift angles, mid-corner smoke signals, and tire howls that are sufficiently vocal to be registered across the border in Italy or Bavaria. With the traction control deactivated, the haute-couture Benz loves to show off. Since there is a fair amount of mass involved, you don't have to corner at cannonball speeds to trigger the action. In a way, the CLS55 is Germany's twenty-first-century answer to the Buick Grand National GNX: not particularly subtle, but a riot for the driver, the passengers, and the audience.
Whereas the CLS55 AMG takes the smart, casual approach to inspired motoring, the M6 refuses to leave its garage without racing coveralls, helmet, and gloves. The BMW is far less happy to trifle with traffic; it prefers to play at a level where more velocity and more skill are at stake. The grippy chassis hangs on much longer, the tires still carving where the Mercedes has long since resorted to stem turns. The stability control permits a higher degree of slip and slide, knowing that the suspension and steering possess enough skill and sensitivity to avoid drama.
Beyond the tree line, where the cows outnumber the cops, the BMW again emerges as the sharper driving instrument. Unlike the CLS, which retains a conservative electronic safety net even when traction control has been switched off, the 6-series is willing to all but drop its electronic guard. In principle, both cars are gifted playthings, but the M6 is more talented and quite a bit more challenging. It tends to need more space because its front wheels like to run wide before the rear end lets go. This is less of an issue on the track than on the road, where the two-door coupe responds nervously to variations of grip and contour.
The BMW is the better driver's car, a title that is clinched by fabulous steering. Fairly meaty and fluent and full of feedback, it needs just 2.4 turns from lock to lock while remaining linear, regardless of vehicle speed. The drilled disc brakes are equally reassuring. They may be noisy at times, but their performance is almost surreal, with enough power to teach your neck muscles a lesson or two. There are some dislikes-notably ride quality only a fakir would enjoy and high tire, wind, and engine noise.
Softer and less radical in the way it deploys its energies, the CLS55 AMG is a paragon of subtle efficiency. The steering may be less direct and lighter but is hardly short of road feel and on-time response. The brakes have a softer pedal but almost the same stopping power. The bigger barge handles a little more ponderously, but it still goes exactly where you point it, graciously defying its extra size and weight.