Steve Maher recommends opening the engine hatch to let the engine run cooler.
I'll buy that at low speeds, but I have to picture that at highway speeds
the area of the breadloaf engine hatch or Vgon license plate door is a low
pressure area that would actually make your engine work harder to breathe.
Certainly the amount of schmutz that a van's tail wears when it's running
rich is an indication that the area doesn't flow a lot of air.

Anyone got engineering input as opposed to my guesswork?

B.
Wm Kennedy
kennedy@admin.njit.edu