Vehicles used by the Arbeiter-Samariter-Bund in Berlin.
A plain Volkswagen Bus, it seems. But, as so often, the devil is in the detail: instead of two common-and garden blue lights, there are electronic flashing lights installed. Quite unusual for any German vehicle, and especially unusual in the removable style.
Please note that these are scans from old 35mm slides in my archives, with resultant deterioration in colours and sharpness.