When calculating a short route
a few hundret meters to the north at http://www.openstreetmap.org/?mlat=48.0407&mlon=11.43729&zoom=16
the route goes along the highway=service instead of the highway=motorway.
The motorway has maxspeed=none the highway=service is set to 30kmh in the style file.
In this case the route should go along the motorway.