Little 3.5 wind motors wouldn't be much good for speed runs - a higher wind means you can run more voltage to achieve the same RPM (shouldn't run most brushless motors past 65,000RPM, with ~40,000RPM being the most efficient spot for 2 pole motors), giving more available power, so you can gear better.
I have a little project car I've thought of doing some speed runs with. Its a nitro RC10GT converted to electric using my own custom parts, with a 540-L brushless motor thrown in. The special battery mounts allow upto 12 cells flat on the chassis, or 16 layered. Thats a LOT of power for a 3KG truck. Enough to backflip at 40mph if your not careful. In theory with the correct setup it has the power for 80-90mph.