Hot on the heels of the all-new SL500 roadster, Mercedes-Benz is unveiling the SL55 AMG roadster to arrive in the United States this fall.
The new SL55 AMG uses a newly-developed, hand-built, 5.5-liter supercharged engine with more than 465 horsepower to reach 60 mph in just 4.5 seconds from rest, making it the fastest production Mercedes-Benz ever.
The SL55 AMG also provides racing-derived braking power to match the horsepower, according to Mercedes-Benz. Immense vented brake discs at each corner and calipers are engineered with what Mercedes calls the industry's first electronic braking system.
Similarly, the SL55 AMG uses a further evolution of Mercedes' ABC active suspension to imbue the car with quick handling reflexes while simultaneously offering ride comfort, according to the German car manufacturer.
The new SL55 AMG will be the latest in the SL line, which began in 1954 with the legendary "Gullwing" 300SL. The 2003 Mercedes-Benz SL55 AMG boasts ABC active suspension and ESP stability control, plus what Mercedes calls the world's first electronic brake system. The new SL55 AMG is capped by a retractable hardtop, giving it characteristics of both a convertible and a coupe.
Visually, the SL55 AMG employs aggressive looks with sculpted rocker panels and rear valence capped off with four chrome exhaust tips and generous 5-spoke, 18-inch forged alloy wheels. The SL55 AMG also tours the world as the Formula 1 Safety Car.
V8 Kompressor - The Dual-Personality Powerhouse
Each SL55 AMG engine produces 465-plus hp and an impressive 516 lbs.-ft. of torque, making easy work of the 0-60 mph sprint in just 4.5 seconds. Every new SL55 AMG's 5.5-liter, supercharged and intercooled V8 engine is hand-assembled one at a time by expert technicians at Mercedes-AMG in Affalterbach, Germany and is bench-tested to ensure performance, according to the manufacturer.
The newly developed V8 engine uses a positive-displacement, Lysholm-type (or screw-type) belt-driven supercharger with scrolling aluminum rotors, providing usable boost virtually from idle speed, and generates a maximum of 11.6 psi boost pressure (or 0.8 bar). The rotors are also Teflon-tipped for more positive sealing and long life. The Kompressor V8 also uses a specially developed crossflow air-to-water intercooler that reduces intake air temperature, creating a denser charge.
Other developments for the Kompressor V8 include a fast-acting electronic throttle, revised cam timing, high-rate valve springs and lightweight valves, according to Mercedes-Benz.
SpeedShift Gear Selection at the Steering Wheel
The SL55 AMG's prodigious torque requires a high-capacity five-speed automatic transmission with SpeedShift programming that nets 35-percent quicker gear changes, according to Mercedes. Those changes can also be accomplished by pressing either of the two steering-wheel mounted shift buttons - left side for downshifts and right side for upshifts.
If asked (by holding the gear lever to the left when in Drive), the SpeedShift transmission can also automatically downshift and can determine the best possible gear for maximum acceleration in any situation. The SpeedShift transmission will also hold a selected gear under high cornering loads, preventing an upshift in mid-corner. As well, a lightweight torque converter can lock up in all forward gears when conditions warrant, according to Mercedes.
Like all Mercedes-Benz cars, the SL55 AMG uses ESP stability control to prevent skids and spins in poor weather driving. However, due to the SL55 AMG's high performance, ESP is programmed specifically for the model, with the high power, handling grip, dynamics and braking performance all playing a crucial role its new programming, Mercedes said.
ABC Active Suspension Lends Agility
The new SL55 AMG's chassis uses a fully independent, double A-arm front suspension and Mercedes-Benz' patented five-link rear suspension. The latter is mated to a substantial steel subframe that takes the place of the SL500's aluminum subframe due to the SL55 AMG's astounding performance levels.
Most importantly, the active suspension is Mercedes' system that it says virtually eliminates body roll in cornering, squat under acceleration and dive during braking. The SL55 AMG uses new software programming specific to the model, loosely akin to increasing the spring rates, shock damping and anti-roll bar stiffness of a conventional suspension.
Mercedes-Benz says its engineers use ABC's interplay of hydraulic, electronic and mechanical parts to reduce body roll by 68 percent (compared to the same vehicle with a conventional suspension), providing the driver with needed feedback through the vehicle chassis. A Sport switch on the center console can alter this, further limiting roll to 95 percent reduced along with tighter shock damping, if the driver prefers sportier handling.
The active suspension system uses four hydraulic servos (or pistons), one on top of each steel coil spring, applying additional forces in response to split-second signals from the ABC computers. Put simply, active suspension solves the traditional old tradeoff between ride comfort and handling precision. The result, according to Mercedes, is that the SL55 AMG exhibits excellent comfort while offering league-leading handling.
Racing-Derived Brakes with 'First Electronic Brake System'
Because of the SL55 AMG's performance potential, Mercedes-AMG says it fits unique braking hardware to the new sportster. All the brake rotors - not just the fronts - are fully vented, and the front rotors measure a large 14.2 inches in diameter, while the rear rotors are 13 inches.
Clamping onto those generous discs are eight-piston front calipers, a direct result of Mercedes-AMG's Championship-repeating Touring Car racing program. Mercedes-Benz, the company that invented ABS anti-lock brakes, traction control and ESP stability control, also offers what it calls the world's first electronic brake system to see production on SL500s, and also on next fall's SL55 AMG. This system provides faster, more sure-footed brake response, especially in emergencies.
The brake pedal works with a computer that tells four fast-acting valves exactly how hard to apply the brakes on each wheel. A backup hydraulic master cylinder comes into play only if there's a serious problem or electrical failure. The system can change brake pressure on each wheel over uneven surfaces and can even increase brake pressure on just the outside wheels when braking in turns, taking advantage of the higher loading during cornering. Even ABS anti-lock and ESP stability control work more efficiently since they are more deeply integrated with the brakes, instead of functioning as parallel systems.
If the driver switches his foot quickly from accelerator to brake pedal, the electronic brake system recognizes the early signs of an emergency situation and reacts automatically. With the help of the high-pressure reservoir, the system raises the pressure in the brake connectors and instantaneously moves the pads onto the brake discs, which can then spring into action with full force as soon as the brake pedal is pressed. At highway speeds, this pre-loading of the braking system reduces stopping distance by about three percent, according to Mercedes-Benz.
In addition, the system automatically senses when the road is wet and imperceptibly applies the brakes just enough to keep the discs dry, so that brake operation remains fast and consistent in the rain.
From Coupe to Roadster in 16 Seconds
At the push of a button, the new SL55 AMG's retractable hardtop can be fully opened or closed in 16 seconds. As the power roof retracts, the rear window glass "spoons" the stowed roof panel, providing a surprisingly large cargo area of 8.3 cubic feet. With the top up, the trunk holds 11.2 cubic feet. A hydraulic pump and 11 computer-controlled hydraulic cylinders power the system, and top operation is controlled by a switch on the center console.
Mercedes-AMG fits the interior with new aluminum trim that has the same texture and look as the sand-cast aluminum supercharger housing. This can be augmented by additional wood trim at no charge, according to the company. AMG gauges with silver dials and an Alcantara headliner also adorn the interior.