Above is the embarrassing (to General Motors) Fortune Magazine cover of 22 August 1982 showing A-body cars from four different divisions with the same paint color. Some background on the matter is here.
The similarity was a cost-cutting measure at the time the corporation was beginning to experience financial constraints due to loss of market share. Thereafter, GM made a greater effort to make its various brands more visually distinctive again.
This post features front end designs of the models shown in Fortune in order to show what effort GM had made on that critical part of the car's brand identification. The Fortune cover cars were posed to maximize their similarity.
My personal experience at the time was that while I could distinguish A-bodied brands from one another, I was strongly aware of how similar the cars seemed overall. When the Fortune issue was published, I nodded in silent agreement.