The CL is Mercedes-Benz's top of the range coupe model. It is in many ways hard to justify as it offers less practicality than the S-Class and lacks the drop-top abilities of the SL, and all three models offer similar performance. Look at it another way however and it is more practical than the SL and sexier than the S-Class. Visually discreet (as much as a five metre long Mercedes can be) it combines wonderfully cosseting accommodation and a gargantuan boot with varying shades of disdainfully powerful engines.
If you have the money to be able to afford to buy and run one then your cars probably don't need to justify themselves.