The extensively freshened CLS gets a new 329-hp, twin-turbo 3.0-liter V6 hooked up to a seven-speed automatic for the base powertrain. The 550 gets a 402-hp, 4.7-liter twin-turbo V8 mated to a new nine-speed automatic. An AMG version with a 577-hp, 5.5-liter V8 delivers ferocious acceleration. Handling is capable and surprisingly agile for such a large car. The ride is firm but supple and steady. The coupelike styling results in a low roof and small windows, reducing interior space. That limits cabin access, hurts visibility, and compromises rear-seat room. Noise levels are hushed. Fit and finish is excellent, but the controls are complicated. All-wheel drive is available.