The Corsa C was introduced with a 1.7 L DTI Ecotec turbodiesel engine supplied by Isuzu (Circle L) with 75 hp (55 kW). This was later joined by the 1.7 L DI Ecotec turbodiesel engine also supplied by Isuzu. The 1.7 L DI Ecotec did not include an intercooler and this reduced power to 65 PS (48 kW). From 2003, a new 1.3 L CDTI Ecotec turbodiesel engine was supplied by Fiat (MultiJet) which produced 70 PS (51 kW) and a 1.7 L CDTI Ecotec turbodiesel was supplied by Isuzu which produced 100 PS (74 kW). This new 1.7 L CDTI Ecotec featured a variable geometry turbocharger.
In addition to its West German home market, the Kadett A sold strongly in what were becoming the manufacturer's traditional export strongholds (notably in Benelux, Scandinavia, Austria and Switzerland). Between February 1964 and the Autumn/Fall of 1965 the cars were also exported to the United States where they were sold through approximately 500 Buick dealers. The same 993 cc engine was fitted and it is not clear whether it was differently tuned for North America: horsepower ratings were differently computed in the USA, following locally devised "SAE" rules: for American market purposes the maximum outputs for the engines were quoted as 46 hp (34 kW; 47 PS) and 54 hp (40 kW; 55 PS).
The high performance of the new Corsa GSi is complemented by the athletic exterior looks featuring large air intakes, sculptured bonnet, prominent rear spoiler and precisely modelled side sills. From the front, the bold Opel GSi fascia with large honeycomb grille and the central Opel Blitz supported by two wings, along with the exterior rear view mirror housings in carbon racing-look become visible. The large chrome-ringed design elements that are visually connected in a horizontal line via black crosspieces running across the front, along with the black traverse cleat on the bonnet support the impression of sportiness. The vibrant styling is also present when viewed from the rear. The prominent spoiler on the edge of the roof creates additional downforce, the sporty chrome tailpipe is framed by the vibrant design of the rear apron in body colour.
But the hot news of the new Kadett B line was the mid-year 1966 introduction of the Rally. Sporting both fog and driving lights, as well as the obligatory racing stripes, the Rally was something altogether new in the small-car market: the first really overt attempt to sell sportiness in the lowest end of the small-car market, at least in the USA. The Ford Cortina GT had been doing it for a few years, but was one class bigger and a fair bit more expensive. The Opel Rally set the template for all the little pocket rockets to come; just like with the big American muscle cars, blatant economy was out, and performance, or at least the impersonation of it, were in.
Unfortunately, Opel’s first victory in the DTM turned out to be as much of a fluke as the podium at Hockenheim. The Calibra’s fell behind once more, and resorted to occupying the lower end of the top 10. The airfield circuit at Diepholz, a third visit to the Nurburgring and the high-speed section of autobahn known as the AVUS-ring were all without meaningful results.
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).