Ok I am aware of racing fuel, along with other "enhancing" additives, however my question is about the best gas to use for a daily driver (if there is a difference). Basing it on my car, with a 305 and a carb, is it better to put say 93 octane in, instead of 87?, is it worse?....does it even make a difference. All I really know is that the higher the octane, the more clean it burns, and the higher the price...however Ive been putting 93 in my car virtually since I've had it. Any suggestions?

 

Run the lowest grade you can without audible knocking. Premium gasolines used to contain more detergents than regular, but it's all pretty much the same now.

 

If your engine doesn't require it, then using it has no real benefit.
Higher octane is just an anti knock index number. For pump fuels, as the octane goes up, the btu output per pound goes down..