The BMW 303 introduced BMW’s first automotive straight-six engine in 1933.
The engine was the 1,182 cc BMW M78, an overhead-valve inline-six developed from the four-cylinder unit used in the BMW 3/20. The 303’s arrival marked a major technical and identity shift for BMW: the company had begun automobile production with small, four-cylinder cars, but the new six-cylinder model established an engine layout that would become central to BMW’s reputation.
The 303 was also significant stylistically. It was the first BMW to use the twin-kidney grille, a design feature that became one of the brand’s most recognizable visual signatures. It was larger than the 3/20 and used a ladder-type frame with independent front suspension, while its body was offered as a two-door saloon or cabriolet.
The model is sometimes confused with the BMW 328 because the 328 became a much more famous prewar sports car. However, the 328 arrived in 1936 and used a later, higher-performance six-cylinder engine. The 303 came first and provided the foundation for related models such as the 315, 319 and 329.