The BMW 309 was launched on the market at the beginning of 1934 after production of the BMW 3/20 PS came to an end so as to avoid losing any part of the customer base. The new car retained the chassis and body of the BMW 303 and combined this with the lower-cost engine of the 3/20. The displacement was increased to nearly 850 cc in order to gain an additional 2 hp and match the power of the engine to the higher weight of the car. At 22 hp, the Type 309 had a rather more modest engine compared with other vehicles available at the time. Customers valued the fuel efficiency of this model combined with comfort that was extremely impressive in this class.