Yes the suspension is on lowest setting.
I will probably lower it about an inch.. at some stage..with lowering links.. The 18" wheels are standard, but in these days of 20+ inch wheels, look a little lost in the arches.. they do give a sublime ride quality though, so I won't be changing them any time soon. A slight drop would improve its stance I think.
I have been trawling pictures of the SL55 from 2003/4 and they all seem to sit quite high on the 18 inch wheels.
John