Bitter SC

The coupé was the first SC model to be introduced in 1979, followed by the convertible at the Frankfurt Auto Show in 1981 and the sedan in 1984. The SC, like the CD, was based on Opel's biggest vehicle at the time, the Senator. It was still in production until 1989.

The outside appearance was inspired by the Pininfarina-designed Ferrari 365 GT4 2+2, which debuted in 1972 and was later offered as the 400 and 412. The SC was powered by either a fuel-injected Opel 3.0-Litre in-line 6-cylinder engine with 177 horsepower or a stroked 3.9-Litre engine with 207 horsepower. Along with the convertible, a four-wheel-drive version of the coupé was introduced in 1981. Ferguson Research created the four-wheel-drive system, which was also available for installation in the Opel Senator/Vauxhall Royale.

Bitter stated during the New York Auto Show in 1984 that it will engage in a limited marketing arrangement with GM to sell the sedan version in the US through participating Buick dealerships. GM aimed to (re)gain market share lost to BMW at the time by being able to provide a premium European product. The possibility of importing Opel vehicles was rejected since it was considered as an entry-level brand in comparison to BMW's luxury reputation. Ultimately, less than a dozen Buick dealers (primarily in the metro New York City region) would carry the Bitter signage, resulting in low sales. Bitter's demise was due to its business strategy and the declining trend of rebodying other manufacturers' vehicles, which had become unfashionable by the 1980s.