Nice cars, but never really cared for the W140 coupes. The W220 coupe always looked a lot better to me.
They are all very big cars, the W220 coupe is as long as my truck.
They are rare because they are one of the most expensive Mercedes you can buy new, and one of the most expensive to own. You need a sturdy check book to sort out the suspension on a W220 coupe.
The C221 coupes look fantastic! Today parked in the center of town I passed a black CL63 AMG with dark tints and very nice Brabus looking wheels. A $150k CL63 would look very good parked in my garage, very good!