Broadly speaking I beleive that wind resistance is generally accepted as being related to the speed cubed.
So by 200mph, even a very aerodynamic car will be starting to lose a lot of power and at 10mph even a very unaerodynamic car will have no problems.

Where between those 10 and 200 points you are has as much to do with power as aerodynamics, with a car like Rod's for example, it has so much power that even with bad aerodynamics and doing 100mph, those aerodynamic effects have little effect on its ability to still accelerate as it has such a large amount of power that even if it takes 70bhp (my guess not an actual figure) to maintain his speed its still a drop in the ocean but at 200mph and 560bhp to maintain the speed it is really starting to take its toll.