Air Inflow in a Vehicle

typically,the same way it came in, only displaced a little. Apart from that it might take the same "flow through" paths provided for normal heating/AC/and vent. Some are located in the doors (a louver appearing device); some in the window weather strip; sometimes under the doors; various other arrangements, including leaky interfaces. When the situation arises where out ventilation can't keep up with inflow, the inflow is impeded or redirected as mentioned in the opening of this post. You might have observed this when trying to eject an object from the forward part of a window only to have it reenter behind you. In this case the air entry point is behind you, the exit point is in from of you.

Many vehicles have extractor vents in the 'C' pillars

Right! And air sometimes flows out under the rear seats.

The term "experience" is very apt. The air coming into the vehicle will frequently be in the form of a directional jet, and at a different temperature to the air inside the vehicle (indeed, it's generally somewhat cooler even than the outside air). Air on its way out from the vehicle will approach the exit point from all available directions, and will generally be at much the same temperature as the remainder of the air in the vehicle.

So, air entering the vehicle will make its presence felt. Air leaving the vehicle is more subtle.

Fyz

What I meant by "experience" is that you really see/realise it if you hold some pieces of paper at any opening availbale inside the vehicle. The pieces of paper definitely are drawn in indicating an ingress of air. In a plain car (without fitted with gadgets like AC, ventilator/ejector etc.) whose windows are open and being driven non-stop for say 25 km, nothing contrary to what I wrote above could be seen/experienced.

Exactly. You don't "experience" it going out because it happens over a wide area and the velocities are small. The actual locations of leaving have been well covered by others, so I was trying to describe why you didn't experience it. Maybe I should have put some more detail to it:

In an air jet, the deflection of your paper would be roughly proportional to the MOMENTUM of the air-flow you are interrupting. A narrow jet will have much higher momentum than a wider one (for the same flow rate). For air leaving the car, the air-flow is widely spread, so you interrupt less air; and, as there is no jet, the momentum for each unit of air you interrupt would be an order of magnitude lower. In addition, once the paper is in place, this slower flow can divert around it, so you don't even get a steady-state deflection that corresponds to the much-reduced momentum. In short, you should expect a deflection that is at most a few percent of the deflection due to the incoming air, and I doubt that you would detect this in a moving car.
If this doesn't convince you, try moving a source of smoke around the inside of the car, and watch where it travels. However, you probably need to close the windows first, or turbulence will disperse it to the extent that you won't be able to identify where it leaves. Please use a joss-stick rather than tobacco, and even then don't allow anyone to breath in any of the smoke (I wouldn't wish to have anyone's ill health either on my conscience - even less in the litigation file).

Fyz

This incoming air is seen as infiltration. Air exiting the vehicle is seen as exfiltration. Depending on the temperature difference between inside and outside and the amount of air in cubic feet per minute, you may get condensation on the inside surface of the glass. If the infiltration of air is greater than the exfiltration, you will have a pressurized space inside the vehicle. If the volumes of air are the same, you will have a balance of pressure equal on either side of the glass inside to outside. What I find more interesting is intake manifold pressure above atmospheric, or lets just call it positive boost. Turbos and superchargers will give you this situation. Can it be done naturally? Yes, it's called ram air.

As somebody who is experienced in the automotive industry, most European cars have vents in the rear quarter panels behind the bumper cover. This is installed for a couple of reasons. What would happen if you slammed the door in an air tight car??? The windshield would pop out of course... The pressure has to be relieved somehow.