5w-40 has not exactly been around as long as European cars have been. 15w-40 is a typical visc for many Euro apps when climate allows. It makes sufficient HT/HS for the A3 spec. As-is now with Euro cars, they tend toward the more spohisticated synthetics with longer ocis. However, imo many newer Euros running synth-length ocis would have been MUCH better served with less-frequent changes of 15w-40. My mechanic shop stocks barrels of Castrol RX 15w-40 and Syntec 5w-50.