It is the Seidel Typ 6/24 PS from 1925, built by the Arop-Gesellschaft Ladisch & Co, Berlin-Charlottenburg. Some very unusual ideas were realized here: the axles consisted of two leaf springs each, the four-wheel brake worked with different intensity on each side of the car when engaged in curves, the brakes and the accelerator could be operated from the steering wheel, the clutch was behind the gearbox and the rear wheel drive, the differential was self-locking,and some more...
At least one car must have been built as it was exhibited at the 1925 Deutsche Automobil-Ausstellung.
(Sorry Joao, I was waiting for this one.
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