1907 is correct, my source calls the vehicle "Dampf-Omnibus" ('steam-bus'). As it is not certain whether that was the official designation, I'll end the puzzle here.
This is your well-deserved next point
Peter Stoltz developed for "Motorfahrzeugfabrik Deutschland GmbH", Berlin different steam vehicles. Krupp AG received the exclusive licence for Germany, in addition to Hanomag, "Eisenwerke Gaggenau AG" also acquired a sublicence.
A speciality of the Stoltz design was the steam boiler. The heating pipes are not mounted in a cylindrical boiler, but on tube plates, so called "Röhrenplatten". These panels goods interchangeable and have withstood pressures of 150 bar during test runs. During tests in the "Mechanisch-Technischen Versuchanstalt", Berlin (mechanical-technical testing institute) the plates are said to have burst only at just under 800 bar.
The expected range of the water supply of 80 km was missed by a wide margin during test drives. Already after 20 to 30 kilometres water had to be replenished. The project was not a success.
I only knows photos of two different trucks and there is to be an sprinkler-truck for street cleaning in Cologne. There is also talk of two buses. One bus was built in 1908 for "Hannoversche Straßenbahn AG" (Hanover Tramway) and was also used there. In 1907 one bus was delivered to ABOAG, Berlin and is to be taken over by Stoltz after his retirement. This bus was transferred to the 'Paris Salon' in 1908 and led to the licence agreement with SAGE.
