I am a big fan of washing my car myself.
However, for a DD that sees northeastern roads in the winter, for me it's worth the peace of mind to run the car through at the end of the winter season, ordering the undercarriage wash to blast all the crap off of the car's underside. I really can't get at this too well in my driveway with my own garden hose.
We have a place in town that my father-in-law trusted, and he was a very particular car guy who had nice cars, and he even ran his black cars through.