They also make the engines used in the Turbostars, and were formally Maybach, who made engines used in the Class 42 Warships and the Class 35 Hymeks. They also make engines for the Bombardier Talent and the Irish 22000 class DMUs. There main areas though are military and maritime engines though, particular for the German Army and Navy.
MTU can also mean Maximum transmission Unit, which is to do with network protocol.