I've been using
Smart Wax One spray to clean my vintage 911 for the past six months and have been very happy with the results. You just lightly mist it on the paint, wipe gently with a microfiber towel, let it dry and wipe it off with another microfiber towel. I can clean the whole car in about 15 minutes.
Like the smart cars it is environmentally friendly, as well. I'm not affiliated with the company- just a happy user.