First Drive Review
This is progress. The 3.0-liter straight-eight powering the Mercedes-Benz 300SLR that Stirling Moss famously drove to victory in the 1955 Mille Miglia produced 302 horsepower. At its 7500-rpm peak, the great sports-racing car topped out at 179 mph.
Fast forward to 2002. AMG, Mercedes' performance arm, has waved its hot-rod wand over the SL500 to create a unique combination of supercar performance and hedonistic comfort. The SL55 AMG is fast, and 55 percent more powerful than the SL.
How fast? There's no simple answer. Officially, the 469-hp supercharged SL55 is electronically limited to 155 mph. But AMG buyers don't spend in the neighborhood of $115,500 to sit in a 155-mph autobahn train and be overtaken by every 911 on the hunt. It seems most European customers (and a small number of Americans) have the restrictor removed. Unrestrained, Mercedes reports the SL55 AMG can run to an intoxicating 208 mph—on the Papenburg proving ground, of course. The problem is tires. No road tires exist for these speeds in a 4400-pound car, so even the "unlimited" SL55 is constrained to 186 mph. That's fast enough to humble a new 3.6-liter Porsche 911, if not quite the 192-mph Turbo.
Without diminishing the "regular" SL's incredible refinement and comfort, the SL55 overlays a level of performance that raises it to the status of true supercar capability. Mercedes' claimed 4.6-second blast to 60 mph—a staggering 1.5 seconds faster than the SL500—can't convey the difference in acceleration, or character, between the two sports cars. The SL55 AMG feels dramatically quicker, as the anticipated numbers indicate. In the 15 seconds it should take the SL55 to reach 125 mph, the SL500 would be at 105 mph.
Nor do they sound alike. Whereas the SL delivers a cultured burble, the SL55's exhaust note is offshore-power-boat racer, the V-8 throb muted on a constant throttle, gloriously assertive when the engine delivers.
The secret, achieved by an IHI belt-driven screw supercharger that spins at 23,000 rpm to a maximum pressure of 11.6 psi, is mountains of torque. At a meager 1500 rpm, the SL55 delivers 369 pound-feet, already 30 pound-feet above the SL500's peak. At only 2000 rpm, 479 pound-feet are on tap. It achieves a peak 516 pound-feet across a plateau from 2650 rpm to 4500. To cope with the torque, AMG exchanged the SL's aluminum alloy rear subframe for one made of steel, a major contributor (a hair less than 88 pounds) to a 243-pound weight increase.
This is instant performance gratification, the breed of responsive, accessible power that, working smoothly with the five-speed automatic transmission, endows the SL55 with instantaneous, horizon-catching acceleration. Mercedes' ESP stability control keeps it in check to the accompaniment of a flashing warning light. Switch off ESP so there's no reduction in engine power when a rear wheel loses traction, and tire-smoking starts are only a throttle tickle away. Yet even on damp roads the SL55 has massive traction.
On the fast, open roads north of Seville in Spain, where AMG held the launch, reigning in the 5.4-liter V-8's 469 horses took more control than we could muster. Inevitably, we arrived at corners up to 50 mph faster than expected, the coupelike refinement making driver and passenger largely unaware of the SL55's rapid progress. Roof-down cruising at 100 mph is also effortless and largely turbulent-free.
The V-8 shares the same capacity as the naturally aspirated engine fitted to the E55, the CLK55, et al., but AMG's engineers have thoroughly upgraded the engine to cope with the increased power. The crankcase, the crankshaft, and the pistons are more durable, oil pressure is increased, and the cylinder heads have been modified to accept the greater airflow. The camshafts produce longer valve-opening times to take advantage of the force-feeding.
