As of Friday this we have a new line between Munich and Split available on GetByBus.com. The whole year line which drives twice a week is operated by Promet Makarska.
From Munich the bus drives the following route, Zagreb, Gračac, Knin, Sinj, Split and Makarska. In the opposite direction it stops in the same places. The routes are operated with comfortable long distance buses, so you should have no problem sleeping while driving.
The bus departure from Munich at 18:00 and arrive in Split 07:00 the next following morning. In addition to this new line we have several other lines driving the route, you can see timetable and read more about that here.
From Split the bus departure at 09:00 and arrive in Munich at 22:00 the same evening, more information about buses from Split to Munich you can find here.
In Munich the bus departure from the ZOB (Central bus station) and in Croatia the bus departure from the main bus station in the cities mentioned above. You can use the station locator on Getbybus to find address of the stations.