The invention relates to a process for multi-layer coating of substrates, in particular vehicles and vehicle parts, by applying two or more coating layers and curing of the applied coatings, wherein at least one of the coating layers is produced from a coating composition which comprises at least one polyurethane binder with free-radically polymerizable olefinic double bonds in the form of (meth)acryloyl groups and with hydrolysable alkoxysilane groups, wherein the resin solids content of the coating composition exhibits an equivalent weight of C.dbd.C double bonds of 200-2000, preferably of 300-1500, and a content of silicon bound in alkoxysilane groups of 1-10 wt-%, preferably of 1-7 wt-%, especially preferably of 2-6 wt-%, and wherein curing of the coating layer, of which there is at least one, proceeds by free-radical polymerisation of the C.dbd.C double bonds on irradiation with high energy radiation and by the formation of siloxane bridges under the action of moisture.