The designation was derived from the taxation class (3), engine power (15 hp with PS being the German equivalent of hp) and DA stands for “Deutsche Ausführung” (German version). The BMW 3/15 PS DA1 had many different body shells so it was one of the first customizable cars. For the first months the production of the car continued as BMW 3/15 PS DA1. When the BMW Dixi line collapsed, BMW took the opportunity and bought the license for the Austin seven as well as the Eisenach factory.
So BMW turned to truck and boat engine, motorcycle and later car manufacture. The Versailles treaty strongly restricted airplane manufacture in Germany and companies had to look for other fields of business. After the end of World War One the situation for BMW - which was founded as an aero engine manufacturer became difficult.