I don't know what the laws are where you are,or if the avgas is the same but last I checked,avgas has TEL (Tetra ethyl lead)why its safe for aircraft but too dangerous for cars who would know?I suspect that it would probably be illegal for use in cars,but just to test,well,You'd have to be really unlucky to get busted.As far as safety is concerned I wouldnt worry at all!It'd be no worse than pump gas.