Unlike most Mercedes, there is no V-6 option for the CLS. The model range starts with the CLS550 and ends with the CLS63 AMG, with nothing in between. That means you have the choice of either a 402-horsepower, twin-turbo 4.6-liter V-8 that bursts up highway on-ramps with aplomb, or a 518-hp, twin-turbo 5.5-liter V-8 that can blow the doors off most muscle cars revving at a stoplight.

The CLS550 has enough power to satisfy most drivers. It's so close to BMW's new twin-turbo V-8 in terms of real-world response that I don't think either company has an edge under the hood. However, the CLS has a nasty habit of lagging when taking off from a dead stop. All the Cars.com editors who tested the 550 bemoaned this attribute. I drove it the most and learned to massage the accelerator pedal just right to overcome most of the lag, but it's hard to pay that much attention all the time.

The E550 features the same V-8 for 2012, but its lack of crisp handling is what might lead more buyers toward the CLS. The CLS may not handle like a sports car, but its steering is precise when taking twisty roads at speed, yet it isn't overly heavy for long highway slogs.

The ride is also surprisingly livable, making the CLS550 nearly as viable a daily driver as an E-Class. The base CLS comes with rear-wheel drive, while the E550 has all-wheel drive standard.