For the CLS 550, this means a 4.6-liter direct-injection twin-turbocharged V-8 engine rated at 402 horsepower and 443 pound-feet of torque. That's a lot of go, and the CLS 550 never feels underpowered. In fact, it feels downright fast in most situations, though the relaxed ride quality and quiet cabin confirm this is the everyday driver option in the CLS Class range.
Zero to 60 mph acceleration takes just 5.1 seconds for the rear-drive CLS 550, or 5.2 seconds for the all-wheel drive 4Matic. Both models come standard with a seven-speed automatic transmission that shifts smoothly, with sport and comfort modes to alter its character to suit the driver's mood.
The CLS63 AMG, on the other hand, adds a more stiffly-sprung, performance-oriented suspension to suit its very potent 518-horsepower, 516-pound-feet of torque, 5.5-liter twin-turbo V-8 engine. An optional Performance Package boosts output to 550 horsepower and 590 pound-feet of torque for even quicker performance.
In standard trim, the CLS63 AMG is still good for 4.4-second 0-60 mph runs and a top speed of 155 mph (electronically limited. The Performance Package shaves the 60 mph time to 4.3 seconds and raises the top speed to 186 mph. A seven-speed MCT paddle-shift multi-clutch gearbox is standard with the CLS63 AMG, offering comfort, sport, sport-plus, and manual (paddle shift) modes.
Where the CLS 550 shows relaxed yet quick pace, the CLS63 AMG is a barnstormer, ready and willing to defy expectations (and logic) with surprising speed, impressive grip, and shockingly nimble handling for a car of its size and heft. A race-start mode helps make launches fast and repeatable, while an LCD display measures performance for posterity. An available $12,000-plus carbon-ceramic braking system offers truly race-worthy stopping capacity, but is overkill for both the wallet and the street.