It's illegal for fuel vendors to sell avgas to people to use in cars so you need to either find someone who plays a little fast and loose with the rules or take a can to the airport to fill and tell them it's for an aircraft engine your testing or some story like that. I read this on an aviation site the other day, perhaps the days of leaded racing fuel are numbered? http://www.avweb.com/avwebbiz/news/Avgas_Safe_Leaded_Car_Gas_Gone_208088-1.html?type=pf
