At a time of rising fuel prices, the need for fuel efficiency was becoming paramount, and Opel decided to change the engine specifications of the Monza. This meant introducing both the inline four-cylinder CIH 2.0E engine from the Rekord E2 (replaced by the torquier 2.2 in October 1984). However, as the Monza weighs almost 1400 kg, given the 115 PS of the two engines, the cars were underpowered and thus unpopular. The 2.5E was given a new Bosch injection system so between 136 and 140 PS was available. The 2.8S was taken out of production. The 3.0E engine stayed the top of the range. The 3.0E was given an upgraded Bosch fuel injection and fuel consumption improved somewhat.