FWIW, with no air flow INTO the 'engine compartment', adding the other bits would create a bit more drag, decreasing your range. Without a wind tunnel, can't say how much. The designers spent a lot of time worrying about how to save money and make the car slicker and to minimize weight to maximize range, that was reasonable for production costs. The CFRP bits were not intended for a large production run - other methods would have been better for the anticipated volume but in the process, they learned a lot about how to do things with that material and it is being used on other models.
2011 535i x-drive GT, 2014 i3 BEV
Soon (hopefully!) A 2021 X5 45e will replace the above