I read an article on this last night. The paint coating is only hydrophobic as long as the surface tension is not interrupted. So soap (or other surface tension breaking liquids) will defeat the coating.
Yeah, "Self Cleaning" is some overblown marketspeak.
While it might be nice for a rainy day or whenyour car gets sprinklerd on, you still have oil/roamgrime, tree sap, insect goo and simple dry road dust that accumulates day after day. Lot more things getting your paint dirty than some muddy water out there.
Nice paint improvement, but "Self Cleaning"... maybe a bit of a stretch
What I wouldn't give to be able to just use a light duster or some compressed air to clean the car after a desert run though!