The BMW 3/15 was BMW's first car, produced in four versions from December 1927 to early 1932. 18,976 BMW 3/15s were manufactured between 1929 and 1932.
In 1927, Fahrzeugfabrik Eisenach, which manufactured automobiles under the Dixi marque, entered a contract with the Austin Motor Company to manufacture the Austin Seven under licence. The first fifty Eisenach-built Sevens were right-hand-drive cars assembled in September 1927 from parts provided by Austin's factory in Longbridge. By December 1927, Dixi had begun building their version of the Seven, the left-hand-drive Dixi 3/15 PS DA-1, built from parts made by Dixi. The 3/15 designation was derived from a taxable horsepower rating of 3 PS with an actual power output of approximately 15 PS (11 kW; 15 hp) The DA-1 designation stood for Erste Deutsche Ausführung (First German Version)
BMW bought Fahrzeugfabrik Eisenach from parent company Gothaer Waggonfabrik in October 1928. As a result, the Dixi 3/15 PS DA-1 became the BMW Dixi 3/15 DA-1.
The main differences between the BMW Dixi 3/15 DA-1 and the contemporary Austin Seven were the addition of Bosch shock absorbers, the placement of the driver's controls on the left side of the vehicle, and the use of metric fasteners.
- Top speed: 75 km/h (45 mph)
- Acceleration 8 to 40 km/h (5 to 25 mph): 10 seconds
- Fuel consumption: appr. 5.5 L/100 km (51 mpg-imp; 43 mpg-US)
The 3/15 DA-2 replaced the DA-1 in April 1929. The main change from the DA-1 was the operation of the brakes on all four wheels by the foot pedal, which had operated only the rear brakes on the DA-1. Other changes included larger tyres and a lower final drive ratio. Available body styles included a steel-bodied two-door saloon, a two-seat convertible, and a delivery van.
3/15 DA-3 Wartburg
The 3/15 DA-3 Wartburg was a sports roadster version of the 3/15, and was consequently BMW's first sports car. A drop-centre front axle was used to lower the frame for a lower centre of gravity. The compression ratio of the engine was raised to 7.0:1, raising power output to 18 bhp (13 kW; 18 PS) at 3500 rpm.
The Wartburg was introduced in 1930, and the Great Depression had drastically reduced the market for sports cars. It was discontinued in 1931, with 150 sold.
The 3/15 DA-4 replaced the DA-2 in mid-February 1931.
While the engine, gearing, and chassis of the DA-4 were unchanged from the original Dixi 3/15 PS DA-1, the DA-4 was a step away from the original Austin design. The DA-4 was the first BMW automobile with independent front suspension, which used the ends of the transverse leaf spring to act as lower control arms, with further wheel location performed by two diagonal leading arms.
The DA-4 was heavier than the DA-2, and a larger wheel diameter was used to compensate for this.
The Austin-based 3/15 series was discontinued before the March 1932 expiration of BMW's licence to manufacture Austin Sevens.
The BMW 3/20 PS was 3/15 successor produced between 1932 and 1934, it was made larger with an 84.6 in (2,149 mm) wheelbase and a body 3 in (76 mm) lower than the 3/15. The new engine was based on the Austin Seven engine used in the 3/15, but its crankshaft ran in plain bearings instead of roller bearings and had an 80 mm (3.1 in) stroke, generating a displacement of 788 cc (48.1 cu in). The new engine design also had a water pump and an overhead valve cylinder head. These design changes caused the engine to generate 20 hp, thereby causing the change in model designation. A swing axle independent rear suspension with a transverse leaf spring was used along with the DA-4's front suspension to give the 3/20 four wheel independent suspension. Four versions of the 3/20 were built: AM 1, AM 2, AM 3 and AM 4, where AM denoted Automobil München.