Prototype Drive
The era of high-revving, naturally aspirated engines has passed its zenith at Mercedes-Benz’s AMG performance division. This October, the 2011 S63 AMG will get an entirely new 5.5-liter V-8 fed by a third-generation direct-injection system from Bosch and two Honeywell turbochargers. Mercedes will offer two versions. The base S63 AMG will have 536 hp and produce 590 lb-ft of torque between 2000 and 4500 rpm. The optional Performance package increases turbo pressure from 15 to 19 psi, raising output to 563 hp with 664 lb-ft available between 2500 and 3750 rpm.
The new engine, internally called the M157, replaces the M156, a naturally aspirated 6.2-liter V-8 that produces 518 hp in the current S-class. This high-revving powerhouse, with its racing-inspired integrated bed plate, was launched a mere five years ago. It can rev up to 7200 rpm, as opposed to the new engine’s 6800-rpm max, and its torque peak of 465 lb-ft is reached at a late 5200 rpm. In other words, it’s a supersized version of a classic sports-car engine.
With Greater Power Comes Greater Efficiency
But the new engine is a far more efficient unit. It is derived from Mercedes’ upcoming turbocharged 4.6-liter V-8, which will power the S550 beginning this fall. Compared with the outgoing 6.2-liter S63 AMG, the mileage of the new 5.5-liter V-8 is in another league. Whereas you get 16 mpg in the old car in the European cycle, Mercedes says the new version returns 22 mpg. Zero-to-62-mph acceleration improves from a claimed 4.6 seconds to 4.5 (4.4 with the Performance package), and top speed stays the same at a governed 155 mph, or 186 mph with the Performance package. We’ve already achieved a 4.5-second run to 60 mph with the current S63, so we expect the actual figures to be in the low fours.
The outgoing model’s seven-speed automatic is replaced by the seven-speed AMG Speedshift MCT gearbox. It’s the same unit found in the SL63 AMG and E63 AMG and is basically a variation of the seven-speed automatic with the torque converter replaced by a wet startup clutch. It can blip the throttle on downshifts and comes with the seemingly inevitable engine stop/start function.
Replacing One Good Engine with Another
We drove a prototype, which felt positively production ready. The difference in character compared with its predecessor is noticeable, although both engines are fantastic. The 6.2-liter offers a more sensitive and delicate throttle response—it feels as if it were wired to your brain and allows the car to charge forward instantly. Acceleration is perfectly linear, and we love the aggressive, racing-like snarl of the 6.2 engine.
The new turbocharged 5.5-liter, on the other hand, pins you into the seat with even more authority—and we drove the lesser version sans Performance package. It has a dark, reassuring, and voluminous growl complemented by the muted hiss of the turbos as you press on. There is some slight turbo lag; not annoying, just different from the behavior of the old car. Gearshifts are quick, superior to and sportier than the previous gearbox’s. Although the 2011 S63 AMG is even faster than the current model, its character is less extravagant and more in line with the expected behavior of a very fast but somewhat portly luxury sedan.
And that’s what this S-class, at about 4900 pounds, still is. The S63 AMG is a confident car, and its limits are high, but in an AMG, we’d prefer firmer steering and a suspension that offers more feedback on the condition of the road surface. The S63’s stability-control system can be switched to a supposed off position, but we had the distinct feeling that the electronic nanny was still watching attentively. From all of this, we deduce that Mercedes believes a lot of S63 customers go for the car because it’s a step up from their neighbor’s S550, not because they are truly interested in its performance capabilities.
The S63 AMG keeps its moniker (now more misleading than ever), and it can be distinguished from its predecessor by the angular dual exhaust tips left and right. We are told there will be a new wheel design. On top of that, it will get some new safety equipment such as a lane-departure-prevention system with brake intervention, which will be offered on all 2011 S-class models.
For the U.S. market, the S63 is once again long wheelbase only, and the price will stay close to the current model’s base figure. But putting it into your garage will be less expensive than before, as it now avoids the dreaded gas-guzzler tax. Eco-warriors, take note: As far as this 186-mph sedan is concerned, there is little ground for lamentation anymore.
