Congratulations on your 500th!
I hope I can also reach such dizzy heights one day.
As a non-German speaker I have been able to translate a certain amount of information on this vehicle as follows:
Imperia Motorvierrad
Constructed by Dr. Ing. Rolf Schroedter for Motorradfabrik Imperia of Bad Godesberg in 1924/25.
It was fitted with a Sperrholzkarosserie (plywood) body and was fitted initially with a 500 ccm-Zweizylindermotor from Breuer. This was later changed to a Blackburne-Motor.
It could reach 100kmh/h and weighed 160kg.
The vehicle was notable for it's clean, simple construction at a very low cost of materials.