You wait Ferdie, for the tirade of abuse to follow from the snow foaming, no touch, pat dry forum members...
(although I do confess I would not be brave enough to go rubbing a dirty car with no water...... )
LOL just realised - bit of a misnomer, there is water involved just not more than a bucket or so. Did you think I was suggesting wiping the gravel off with a damp jay cloth
ONR is an 'odd' 1:500 solution that seems to roll off the paint (allegedly) taking the dirt with it