Air Infiltration in car cabin

I understand some cars are having three modes of air entry.
1. 100% Fresh air
2. 100% Recirculated Air or
3. % of recirculation based on setting

100% Fresh Air Scenario
Vehicle say 80 kmph, Window glasses closed in driving.
Vehicle is in 100% Fresh air say 8-10 kg/min is sucked from outside and blown inside the cabin
The only major body opening is AIR EXTRACTORS from the rear side of the vehicle.
So. As the air is pumped in, the pressure inside the cabin increases to certain Pascals, and a balance is formed when
Air coming in = Air going out of AIR EXTRACTORS

So the cabin be at little higher pressure, than "normal without blower condition".

100% Recirculation Scenario
Vehicle say 80kmph, Glass closed, only air entry or exit is possible thro body leakages and air extractors

Now blower sucks the air from inside the cabin, say 8-10 kg/min.

Whether this blower action will be sucking even air from outside the car thro AIR EXTRACTORS or Body leakages?

What is air infiltration? or how much the air may flow in? Is there any empirical relationship between vehicle speed and air infiltration?

Whether cabin pressure will go down below "normal without blower operating pressure"? I mean sucking or negative delta pressure?