of the vehicle. I'm not sure how much physics you ever had to take, but here is a nice quick overview of the concept of work:

So we have a truck, which for simplicity we will treat as a rectangle like in my sketch above, with a cross sectional area A. It has some fancy device inside to reduce or eliminate the pressure in just front of the vehicle. Let P be atmospheric pressure. The work W required to eliminate the pressure in front of the truck is give by the force needed to push back the atmosphere (P*A) times the distance D traveled. W = P*A*D.

But notice that this is exactly equal to the work done by the atmosphere on the back of the truck. You cannot get any more work out of this than you put in, and when you factor in inefficiencies in the pressure decreasing device it is a losing battle.