In the early 1920s, Opel became the first German car manufacturer to incorporate a mass-production assembly line in the building of their automobiles. In 1924, they used their assembly line to produce a new open two-seater called the Laubfrosch (Tree frog). The Laubfrosch was finished exclusively in green lacquer. The car sold for an expensive 3,900 marks (expensive considering the less expensive manufacturing process), but by the 1930s, this type of vehicle would cost a mere 1,930 marks – due in part to the assembly line, but also due to the skyrocketing demand for cars. Adam Opel led the way for motorised transportation to become not just a means for the rich, but also a reliable way for people of all classes to travel.

Opel was marketed in Malaysia beginning from the 1970s, and early models exported were Kadett, Gemini, and Manta. Opel had moderate sales from the 1980s until the early 2000s, when Malaysian car buyers favoured Japanese and Korean brand cars such as Toyota, Honda, Hyundai (Inokom) and Kia (Naza), which offered more competitive prices. Sales of Opel cars in Malaysia were dropped then, as Opel's prices were slightly higher than the same-segment Japanese, Korean, and local Proton and Perodua cars, and they were hard to maintain, had bad aftersales services, and spare parts were not readily available.
The Buick Regal is a rebadged Opel Insignia.[56] The main differences are the modified radiator grill and the altered colour of the passenger compartment illumination (blue instead of red). The Regal GS is comparable to the Insignia OPC. It was first assembled alongside the Insignia at the Opel plant in Rüsselsheim. Since the first quarter of 2011, it is now being built on the flexible assembly line at the GM plant in Oshawa, Canada.[57]
The GSi's engine mapping had been carried out by Opel tuning specialists Irmscher. A model with the 82 PS (60 kW) 1.4 L multi point fuel injected engine, which was otherwise mechanically identical to the GSi, also became available as the Nova SRi in the United Kingdom. In January 1988, a turbocharged version of the Isuzu diesel engine was introduced, with power increased to 67 PS (49 kW).[8]