The flaps on the roof of a NASCAR car are operated when laminar flow gets under the small lip which is then presented to the air when the car is going in reverse. The hood flaps are operated by air actually being baffled by the front wheels and then directed upwards.
What was pointed out to me this morning, is that a V8 Supercar when travelling in reverse, the whole rear window which is virtually unblocked by the rear wing, is presented as a leading surface to the laminar flow of air and provides more downforce than the rear wing which itself provides almost negligible lift in the wrong direction.
In comparison the "Big Ass Spoiler" on the back of a NASCAR cup car actually presents a bigger wall to the air in reverse; more of that air is directed underneath the car than otherwise would have been with a separated wing element.
Also, if I was Grand Poohbah and Lord High Everything Else, I'd have indicators that actually worked. I don't know how many accidents have been caused pointlessly due to people trying to enter the pits. For goodness sake, they already have stickers where the indicators are already supposed to go.