Founder Erich Bitter (1933-2023), a then retired racing driver turned automobile tuner, importer and ultimately designer began crafting his own vehicles after business ventures with Italian manufacturer Intermeccanica ended.

The Bitter CD, a three-door hatchback coupe featuring a 227 hp (169 kW) Chevrolet V8 with a 327ci displacement, was built between 1973 and 1979.

The doors would adopt a conventional opening system and the bumper bar, windshield wipers and other parts would be derived from the Opel Diplomat in order to facilitate production and maintain costs.

However, because he did not have the necessary capital and other resources to set up his own production facilities, Bitter turned to Baur GmbH in Stuttgart, as a proven independent small-scale manufacturer.

Dave Holls and Opel's design team supplemented the design with a small front spoiler, larger grille, higher bumper bars and by prolonging upwards the lower edge of the rear side windows across the C-pillar to the rear hatch.

The Baur team also engaged in significant development work, which included manufacturing a hard foam mockup.

Their role then extended to manufacturing the CD body panels, assembling the shell, preparing interior as well as installing the Opel Diplomat's mechanicals.

Overheating concerns precluded fitting a turbocharger and instead Erich Bitter opted to add displacement.

Referred to as a 3.9-litre (engine code M39E, the "M" for Mantzel), this version appeared in 1984 and produces 210 PS (154 kW) while also offering fifty percent more torque.

OCRA, however, did not have the means or experience to series produce bodies and lost the contract in early 1982, after 79 examples had been built.

In 1984, Bitter announced at the New York Auto Show that it would enter into a limited marketing agreement with GM to sell the coupé version in the United States, through participating Buick dealerships.

By being able to offer a premium European product, GM had hoped to regain market share lost to BMW at the time.

The option of importing Opel cars was dismissed on the basis that it was perceived to be an entry-level brand, relative to BMW's premium status.

Ultimately, fewer than a dozen Buick dealers (mostly in the metro New York City area) would bear the Bitter signage, resulting in minimal sales.

[9] Relative to the donor car, the Vero features unique restyling claimed to have cost A$1 million,[10] which took about a week to install.

Its leather-trimmed interior featured luxury fittings from the donor car such as a DVD player and screens in the back of the front headrests for rear passengers.

The donor car's Chevrolet V8 6.0-litre 362 PS (266 kW) engine, with a six-speed automatic transmission, remained unchanged.

[16] The Bitter Type 3 was a 2+2 seater convertible introduced in 1988 as the successor to the SC and primarily intended for sale in the United States.

At the end of 1988, the first American sales brochures were printed, but before production of the car could start, GM withdrew its plans.

[16] Also based on the Opel Omega A, Bitter developed a four-door sedan whose lines essentially corresponded to those of the Type 3 convertible.

The Tasco was a two-seat, mid-engine, powered Chrysler sports car that Bitter developed with Japanese funding.

Bitter continued to pursue the concept of modifying powerful Australian GM vehicles for the European market with the Vero model.

[16] The Bitter SC was the subject of a sub-plot in episode 9 of season 6 of The Goldbergs (2013 TV series), "Bachelor Party".