Here's a very good video from the X-Prize Knockout Round (and I appear fleetingly in the background).
Also, notice the gray-ish air *scoop* on the side of the #98 car as it appears around 0:48 seconds. I wonder if this helped keep things cooler -- I suspect that it did; because the NACA intake is recessed into the side of the car that is already set at an optimal angle for low drag. So, the air would not be able to "close in" fast enough for the NACA intake to gather much pressure. They do have the exhaust vent ideally located, right on the trailing fascia, so there would be low pressure developed there, to help draw the air through the engine air plenum.