The WRC takes totally standard affordable hatchbacks, strips them to the shell, and fills them with racing components and top-grade aerodynamics. Now you can see all that aero, painted in dust.
This video is from the Acropolis Rally in Greece a few weekends ago. It's amazing to see what looks like dust shooting out of the rear window. What you're really seeing is very refined management of high and low pressure zones to keep the car stable at high speed.
Don't expect that Chevy Cavalier with a bare metal wing on the back to be this competent.