Hi, The most common expression is Stundenkilometer and, less often, Kilometer pro Stunde for km/h.
I never heard or used Kilometer-Stunde, as was suggested by the Dutch gentleman, but I lived in southern Germany. Yours, Gordon Aubrecht Professor of Physics OSU Physics (614) 292-2574, FAX (614) 292-7557 Marion Campus (740) 389-6786, ext. 6250, FAX (614) 292-5817 check out my web sites through my home page http://www.physics.ohio-state.edu/~aubrecht Physics is like sex: sure, it may give some practical results, but that's not why we do it. --Richard Feynman.
