The wind speed of air hitting a tire at 220 mph, is 220 mph. Wheels are draggy only because they produce massive flow separation and impart large amounts of energy into the air flow due to their rotation. Closed wheels reduce drag by removing the separation and preventing the wheels from imparting energy into the air, but a closed shape can still be very draggy.
There is also skin friction drag, even a shape with zero frontal area that is perfectly flat will produce drag. The boundary condition between the solid body and air is must satisfy the "no slip" condition. That is, air is pulled along at the velocity of the solid body exactly at the body's surface. This means that momentum is imparted into the otherwise still air, and this becomes a force on the body.
The major source of drag for a car is pressure drag, and possibly induced drag if it produces large amounts of downforce. Stagnation occurs at the front of the vehicle, generating a high pressure zone which pushed the vehicle back. In a simple flow model known as potential flow, the air moves around the body and produces a rear stagnation point that pushes it forward and reduces drag to zero. Unfortunately in real life, the adverse pressure gradient that results from this causes the air flow to separate from the body and create a low pressure zone at the rear of the car. This pull the car back and slows it down.
I'm an aerodynamicist too.
Of course, but there are only so many ways to do things before you become outright wrong. I haven't tried to confirm it, but GT5 is roughly correctly in modeling how drag works. There are other parts of the aerodynamics that are horribly incorrect.
