The S-Class is brimming with features and qualities that make it stand out among luxury cars. A powerful 4.7-liter turbo V8 provides effortless acceleration and delivered 18 mpg overall in our tests. The S550 brings a whole host of advanced technology, including the ability to follow the road and stop by itself in an emergency. The ride is very plush, commanding, and steady--the best we've ever tested--and the cabin is ultrahushed. Even though it's large and posh, handling precision is commendable. Many controls are overly complicated, however. A coupe version is available, and a plug-in hybrid is new for 2016. A convertible version is due out in the spring. Reliability has been well below average.