For any considering using leaded gas on public roads, you should know that "the Clean Air Act of January 1, 1996 banned the sale of leaded fuel for use in on-road vehicles. Possession and use of leaded gasoline in a regular on-road vehicle now carries a maximum $10,000 fine in the United States. However, fuel containing lead may continue to be sold for off-road uses, including aircraft, racing cars, farm equipment, and marine engines."
http://en.wikipedia.org/wiki/Antiknock_agent