Volvos (among others I presume, since this feature is 4 years old by now) do that http://www.youtube.com/watch?v=tPO6iRetpyc

Only both Volvo [1] and Mercedes [2] both forgot to switch the system on for the press!

[1] http://youtu.be/QJ6z3IArINI?t=32s [2] http://www.youtube.com/watch?v=XBy78UJ081w

Thanks. Unless they were prototypes I don't understand why the system isn't always on, or at least difficult to turn off.

Actually this tech does exist on the S-Class (and presuably the CL as well).

Those cars are still a little beyond my grasp -- I had a C and now a CLS -- but the wonderful thing about this tech is watching it trickle down from the top of their range down through the $32,000 C Class.