Rather than going to a car wash I have been using Chemical Guys 'Swift Wipe Waterless Car Wash'. This is incredible stuff, it seems to lift dust and dirt off the surface as you wipe instead of grinding into the surface, leaving it smooth, shiny and slippery. The nice thing is water with minerals never touches the surface of my vehicles. I have used this Waterless Car Wash on an MKZ, MKX and now my Nautilus with great results.
I purchased one of these...
Amazon.com
...to make it easy to apply. With this mop and it's curved handle I can reach the roof and entire front window. Just spray and wipe the mop head over it until it dries a bit or use the second mop head to go over the entire vehicle. It's easy to do and I get done in a short time. Safe on chrome and glass but I found 90% alcohol (using same mop head) is easiest way to do the windows (and quickly self dries).
Almost forgot to mention, smells good too, kind'a like bubble gum