The accident, which occurred around 0400 GMT, left eight others seriously injured.
The coach, chartered by a travel company, was carrying a group of around 50 Filipino tourists to the Oktoberfest in Munich, a spokeswoman for the Upper Bavaria police prefecture told AFP.
According to initial findings from the investigation, the vehicle left the road before overturning near Buchloe, in a region close to the Austrian border. It had departed from the town of Mailand.
Significant emergency resources were deployed at the scene and the motorway was closed in both directions.
