Originally Posted by
Rick_L
I think you're right markm, except for one thing. Race gas and avgas don't have the federal road gas tax added in to the price. And they sometimes make the disclaimer on that with race gas. So you're not paying the taxes owed, which is also illegal. This doesn't apply to high octane gas sold for the street, which is taxed (and unleaded).
The other half of the avgas story is the distillation curve. It's meant for flying conditions (altitude and temperature range). Race gas comes in a wide range of distillation curves, but is more generally like street gas.