The Opel 7/34 PS is a large but relatively inexpensive six-cylinder-powered car manufactured by Opel, introduced in October 1927. It was replaced in 1928 by the Opel 8/40 PS which was virtually identical except that the cylinder capacity had been increased. Significant changes to the chassis took place in February 1929, after which production of the model continued till September 1930. The 8/40 PS was replaced by the Opel 1.8 Liter in 1931, also a compact six-cylinder car.

The Opel 1.8 Liter is a family car manufactured by Opel. Production commenced in January 1931, and continued till November 1933. The Opel 1.8 Liter was the first new Opel to be launched following the purchase of an 80% share in Opel by General Motors (GM), and the first Opel to have been designed and developed by GM in North America.