Where the Mercedes starship scores is on comfort. Real sports cars don't have to be fitted with torture-chamber seats and crash-bang-wallop suspensions. The CLS has rear seats that can actually accommodate human beings, along with bigger and more adjustable (but not more supportive) front chairs, a quieter cabin, and a much more compliant chassis. Despite its ground-hugging stance, the Mercedes rarely underestimates the depth of a rut or the viciousness of a manhole cover. As a result, it feels more relaxed and composed.
Tech-savvy kids may love iDrive and the seemingly endless modes you can dial into the M6's electronic brain, but very few of them can afford this car, which is aimed at forty-five-year-old-plus affluent males. The clientele's programming skills probably don't reach far beyond the M button on the steering wheel, yet you have to program the settings for it via iDrive. Then you can instantly summon your favorite setup-like P500 (for all 500 horses instead of only 394), M Dynamic (between DSC on and off), the desired shift speed, and the stiffness of the electronic dampers. In M mode, the standard head-up display is activated, depicting gear position, digital road speed, and analog engine speed. Theoretically, you can push the lever into D and let the chips sort out the gearchanges, but that's dreadfully slow and coarse. Best leave it in S and use your index finger to click higher or lower ratios. In the most eager setup, the wizard transmission will shift up in a matter of milliseconds, and it will automatically blip the throttle before switching cogs.
On any demanding stretch of country road, the BMW's sequential transmission is both intuitive and inspiring. In everyday driving conditions, however, its performance is questionable. The predetermined mix of shift speed and throttle response is wrong more often than it's right, and the automatic setting is still too abrupt for day-to-day driving. That's exactly why BMW is preparing a conventional manual gearbox for the American market.
Those who don't care about swapping gears should consider the CLS55 AMG. Its five-speed manu-matic comes with steering-wheel-mounted shift buttons, but the black box is actually so sensitive, smooth, and slick that you can give your digits a rest. A quick learner, the electronic brain adjusts promptly to individual driving styles and preferred patterns. As long as you don't mind the mileage penalty, you can pull the lever down to S and leave it there.
On the autobahn between Garmisch and Munich, it doesn't really matter whether there is a V-8 or a V-10 in charge of propulsion. Maximum speed of both cars is a governed 155 mph, and the 0-to-60-mph acceleration time differs by a token tenth of a second (4.5 seconds for the Merc, 4.4 for the BMW). Although the M6 may be a tad quicker between 100 and 150 mph, any advantage is soon neutralized by traffic. On the secondary country lanes that take us toward Salzburg, however, the different characters of the two engines lead to different rhythms and driving styles.