Safety, Reliability & Mileage
The CL has not been crash-tested by the Insurance Institute for Highway Safety, nor is there reliability data for it. The CL550's mileage is estimated to be 15/23 mpg city/highway, and it takes premium gasoline.
CL550 in the Market
The CL550's price is enough to guarantee it a solid spot in the market. In other words, if you can afford more than $100,000 for a car that doesn't have rear doors, who cares if it's not the fastest version out there? I doubt you'll feel like you're getting ripped off by not choosing the more powerful CL600 or an AMG version. The CL550 is still a stunner.
And that's the appeal of the CL550: It's not something I judge by how well it carries groceries, handles child seats or rips around a racetrack. It's more logical to judge it by the luxury experience it provides, and in that sense the CL550 does quite well.
If your criteria include owning the most beautiful car on the block, and having it also be luxurious and comfortable, it will be hard to find something better than this.
See also:
General notes
    WARNING
If the vehicle becomes trapped in snow, 
ensure that snow is kept away from the 
exhaust pipe and from around the vehicle as 
long as the engine is running. Otherwise, 
poisonous carbon  ...
   
Infrared reflective windshield
   The infrared reflecting glass prevents the
vehicle interior from becoming too hot. It also
blocks radio waves up into the gigahertz
range.
In order to operate radio-controlled
equipment, e.g. t ...
   
Vehicle remote opening
   If you have unintentionally locked your 
vehicle (e.g. the SmartKey is still in the 
vehicle) and a replacement SmartKey is not 
available, the vehicle can be opened by a 
Mercedes-Benz Customer A ...
   
