2007 Mercedes-Benz SL55 AMG

A funny thing happened at the 1934 Eifelrennen race at the Nürburgring. Alfred Neubauer, the Zeppelinesque chief of the Mercedes team, directed his crew to grind off all the bone-white paint that distinguished the Benz factory racers.

Hence the origin of silver as the German color for racing. But that's not the point. Neubauer's motive had nothing to do with aesthetics. In those days, the competition weight regs specified a maximum limit, rather than a minimum. Neubauer's paint trick was designed to get the cars down below the max. The rulemakers set an upper limit, because they saw weight as a dynamic asset. A bigger car would have a bigger engine, and thus go faster. The objective was to slow the cars down. Ha.

This story came to mind early in our first lap of Wisconsin's Road America racetrack in the new Mercedes SL55 AMG roadster. The Neubauer parable flickered in my mind's eye like a prewar movie as I hit the rumble strips on the exit of Turn Five and started up the hill. Wow. Was ist los?

See, getting out there onto the exit curbing was not the intent upon entering the turn. First lap in a new car — and an expensive one at that — lots of power, cold tires, etc. Easy does it. But when the throttle went down at the apex, the car was across the track and onto that alligator curbing before you could say, "Götterdämmerung!"

This little tableau, reinforced by other examples of mass exerting its relentless influence, emerged as the overriding impression of an all-too-brief Road America experience, laid on by Mercedes-Benz as the finale of its North American SL55 AMG press launch. Given the car's capabilities, it was certainly the right venue — long straights punctuated by hard braking and generally uncomplicated turns. No esses, no tricky transitions. Moreover, Mercedes had enlisted a platoon of pro road racers to demonstrate those capabilities as dramatically as possible. The demos came after we ordinary mortals had done a few laps, and with a light rain at the end of the session, this became quite dramatic, indeed.

But as we strapped on a new SL55 to head home, the nagging question persisted: What's up with all this avoirdupois? The standard SL500 we tested last April was certainly no wraith. When the readouts on the C/D scales finally settled, the tally for that one stood at a resounding 4172 pounds. That's SUV territory, but even so, the AMG version is heftier: 4411 pounds. What's the deal? Weight is the enemy. These guys must know that.

Make no mistake, this is a formidable automobile, Moby Dick mass notwithstanding. Check the motivational specs: 493 horsepower at 6100 rpm, 516 pound-feet of torque manifesting itself along a wonderfully flat curve from 2650 to 4500 rpm. It's the most potent Benz ever offered in North America, according to the manufacturer, and also the quickest factory Benz we've ever tested: 0 to 60 in 4.5 seconds, 0 to 100 in 10.9, the quarter-mile in 13 seconds flat at 110 mph.

In contrast, the SL500 tested in our April issue hit 60 mph in 5.8 seconds, 100 in 14.5, and covered the quarter in 14.3 seconds at 99 mph. The disparities seem minor on paper, but the real-world distinctions are dramatic. Crack the throttle, and this posh heavyweight lunges forward like a shark that's been invited to nibble a chunk of Britney Spears. It dissects traffic like a superbike and exudes a sense of mechanical resentment when a soulless microchip arrests the rush at 156 mph.