What would the calculation look like when computing the wind pressure of a moving vehilce versus compressed air pressure pushing against the the moving vehicle, how much compressed air pressure would be needed to combat the wind of the moving vehicle.?
I think you are asking what is the air pressure caused by a vehicle moving?
It's a little complicated for a real vehicle with aerodynamics and air moving around it - but if you imagine a simple shaped object the force is
Which says that the force from the air is 1/2 * density of air * velocity squared * drag coeeficent * area
But since pressure is force / area we can drop the area bit and have the pressure of air just depends on the speed (v^2) and the shape Cd
You can look up Cd for different shapes, see http://en.wikipedia.org/wiki/Drag_equation. But it's generally between 1 for a flat plate and 0.05 for a very streamlined teardrop.