In the fall of 1970, Opel presented its completely new vehicle range in Rüsselsheim (internal project code 1.450). The Opel Manta coupé was launched on September 9, followed by the Opel Ascona on October 28 in two- and four-door sedan forms, plus a three-door station wagon called the Caravan or Voyage. These models were positioned between the existing Opel Kadett and the Opel Rekord.

The Ascona was developed as a replacement to the Kadett, but late in the car's development Opel chose to instead develop a new, smaller Kadett and instead positioned the Ascona as a competitor to the successful Ford mid-sized Taunus range. The Opel Ascona A stayed in production until 1975. By that time, almost 692,000 vehicles of the first series had been produced.

The range featured petrol engines from 1.2 L to 1.9 L, with power between 60 PS (44 kW) and 90 PS (66 kW). The 1.2 L had an overhead valve (OHV) head, while the 1.6 L and 1.9 L featured the Opel cam-in-head engine (CIH). The CIH was a compromise effort, with the camshaft mounted next to the valves rather than above them. All used a single barrel carburetor. Even with this simple design, the Ascona 1.9 SR had a successful career in motorsports, with Walter Röhrl winning the European Rally Championship in 1974. Tuner Steinmetz developed a special version of the Ascona SR, with two single-barrel Solex carburettors, lifting power to 125 PS (92 kW).