I am not sure if the earlier
I am not sure if the earlier grill design was so much made to copy the Mustang's, I think that having it all blacked out was to look more powerful and menacing. The problem was without the bumper bar being painted body color it looked to many like the whole front end was missing. I frankly thought it looked awful, and I am glad that they returned to the body colored bumper bar, as it integrates the nose of the Camaro with the rest of the car. Both the Camaro ZL1 and the Ford GT500 needed bigger grill openings to allow for additional cooling of the supercharged V8 engine, transmission and brakes, but like using a bigger rear wing and aerodynamic trim, the open grill and aero bits look much more fitting on the most powerful models, and less of a poser bolt on as they can on entry models. One important thing that people don't think (or know) about is that the 6th Generation Camaro moved to the lighter GM Alpha platform chassis, which shaved of 200+lbs, making it far lighter than it's current Mustang and Challenger ponycar rivals. This is why the Camaro SS is quicker than the Mustang GT which has similar power, and how the ZL1 Camaro can keep up with supercharged V8 rivals that have FAR more power, but are heavier, and often do not handle as well.