The Irmscher GT is a coupe built by Irmscher, the German tuning and coachbuilding firm based in Remshalden that specialized almost exclusively in modifying and re-bodying Opel vehicles, including a small production of a Spider version of the Opel Corsa through a Spanish subsidiary. An early study for the car, still closely resembling the Opel Manta, was shown at the Frankfurt IAA in September 1987. A revised version intended for series production was presented at the Geneva Salon in 1988, by which point the design had moved away from any Manta resemblance, adopting softer, rounded forms that were said to recall Bitter's smaller models of the period. Despite its production intent and favorable market prospects, the Irmscher GT remained a prototype and was never put into series production.
The car was a 2+2 seat coupe with two doors, built to a high standard of interior trim, an area in which Irmscher specialized. Its smooth-surfaced body and fully enclosed underbody produced a drag coefficient of 0.273 and were designed to minimize lift at both axles. The floorpan and mechanical basis came from the Opel Omega 3000, with the plastic body bonded to the Omega chassis using modern adhesive techniques. The engine was moved rearward in the chassis compared to the standard Omega layout to improve weight distribution, though the wheelbase remained identical to the Omega's at 273 cm. Overall length measured 459 cm, placing the car between the Manta and the Omega in size; width and height were 178 cm and 134 cm respectively.
Power came from a six-cylinder engine enlarged to 3.6 litres, the same unit Irmscher supplied to Opel customers, fitted with a catalytic converter and rated at 200 hp. Irmscher also offered this engine for the Senator. Running gear drew on Omega 3000 components, including a five-speed manual gearbox, McPherson front suspension, a semi-trailing arm rear axle, and an anti-lock braking system. At a weight of 1330 kg, the Irmscher GT was claimed to accelerate from 0 to 100 km/h in 7.9 seconds, with a top speed of 245 km/h. Although conceived with a convertible variant in mind, the car was shown first as a coupe, and it never advanced beyond the prototype stage.
