av gas is not pure gasoline that is a myth that is old as I can think of. IT has a much higher lead content.

The main petroleum component used in blending avgas is alkylate, which is essentially a mixture of various isooctanes, and some refineries also use some reformate. Avgas has a density of 6.02 lb/U.S. gal at 15 °C, or 0.721 kg/l, and this density is commonly used for weight and balance computation. Density increases to 6.40 lb/US gallon at -40 °C, and decreases by about 0.5% per 5 °C (9 °F) increase in temperature.[1] Avgas has an emission coefficient (or factor) of 18.355 pounds CO2 per U.S. gallon (2.1994 kg/l)[2][3] or about 3.05 units of weight CO2 produced per unit weight of fuel used. Avgas has a lower and more uniform vapor pressure than automotive gasoline, which keeps it in the liquid state at high-altitude, preventing vapor lock.

Buy real race like c112. I run in it my stocker and it has a real distictive smell to it. But beware you can get heavilly fined running race gas in your car. It has lead in it and the federal road taxes have not been paid on it.