is it a bus, is it a tram?

Actually it is a double-deck railbus or as it is put in German, a Doppelstockschienenbus of the Deutsche Bahn class 670. Builders were the Deutsche Waggonbau AG (DWA). It is a bit like a bus as it is diesel powered, two-axled and several parts are used in bus construction. This one is painted in "Fürst Franz" livery of the Dessauer Verkehrs- und Eisenbahngesellschaft (DVE) and entered use as such for the new operator (one of two of this class operated by DVE) last month.

Specifications of the 670 class

Numbering:  670 001–006
Units:  6
Builder:  DWA
Build year:  1996
Axle order:  1'A'
Gauge:  1,435 mm
Length over buffers:  16,332 mm
Height:  4,630 mm
Width:  3,070 mm
Wheelbase:  9,000 mm
Service weight:  34.25 tonnes
Top speed:  100 km/h
Power:  250 kW
Motor type:  MTU 6V 183 TD 13
Revs:  2100 rpm
Transmission:  hydro-mechanical
Tank capacity:  555 l + 255 l
Brakes:  Disc
Train heating:  Warm water, oil supplemental heating
Seating places:  78
Standing places:  32
Floor height:  600 mm
Seating classes:  2