So...hypothetical question, just to resurrect this for no reason:

If I were to put this on my F56s, would you suggest getting a short one to place in front of my sun roof, so that I can make sure the bottom is hollow to dump high-speed air on my head, or would that create too much drag, since there wouldn't be a place for the air to escape out of the car, unless my windows are rolled down? But if my windows are rolled down, would that allow the air coming from the roof-scoop through the sun roof to escape, or would there be too much air coming in from both the sun roof and open windows, creating said recirculation bubble, and producing mass turmoil as a byproduct, endangering everything near the vehicle.

OR should I place it on top of the sun roof, in order to minimize the amount of ambient air being dumped into the cabin, negating the positive effects of the HP robbing AC system that I'll undoubtedly be running?

Regardless of which aforementioned placement of said gorgeous hood scoop, how much HP does a windshield JCW sticker add?

 

it would create more drag, how much? not sure it would all depend on the aerodynamics of the car and the size of the scoop.

 

The reason the WRC cars and the Renault Trophy cars run the roof scoop is to get air into the cockpit they don't have what we would consider OEM air flow through the interior of the cars... well the Renault uses it to feed air to the engine as well, the Trophy cars are a little MODed, they are converted to mid-engine and the driver is moved to the center of the car, getting fresh air from the scoop and the the rest of the air is directed to the CAI for the engine.

...and it really only develops drag if the air it scoops in has no where to go, if your MOD goes as far as to channel the air through the cockpit and out of the car the drag is mitigated.

I have seen the DRS style wing mounted a few MINIs, takes a little coding to do correctly, so the driver can touch a button to open the wing for the DRS effect, tap the brake to close the wing, and in one example I saw step on the brake and the wing acts as an Air Brake like the Bugatti.

The MINI that had that rear wing was on is a supercharged twin turbo 1.6L example of MADNESS it boasted a 0 to 60 time of sub 3 seconds and could stop in close to three car lengths. Do I want to have a MINI like that? Yes, yes I do.

Motor on!

 

Drag is a funny thing. Actually, air flow is a funny thing! If air does not have any place to go, like if you were to block off the front of the scoop, it will tend to just sit there. Often, the mass of air sitting there will start spinning, acting as a "bearing" and helping more air go up and over the scoop!

An open scoop could wind up producing "interference drag" as the shock waves of the air going into the scoop bounce off each other. That would mostly affect the air in the scoop, and not much the air going past it, but...

All that said, such effects are going to be a whole lot less than that of a bike rack (e.g.). And people usually don't have any problem sticking that on their cars, right?