These two Porsche 911 models are two modifications of the same model with one major difference, the modifications. First of all, there is a $54,500 difference in the base MSRP. The 2016 Porsche 911 Coupe R has a higher starting price than the 2016 Porsche 911 Coupe GT3. Also, the 2016 911 Coupe R has bigger and thirstier engine; the 2016 911 Coupe GT3 gets 1 more mpg. In addition, you'll seat two more passengers in the 911 Coupe GT3 than in the 911 Coupe R. Among similarities are the body structure, market segment, ground shadow size, and height.