Originally Posted by Airhead Wrangler
I actually get slightly better mileage on mid grade than regular at 8.2:1. Explain that. No, this was not a single tank freak occurence. A guy I was riding with told me he got slightly better mileage running mid grade in his thumper, so I called bullshit. I alternated between regular and mid grade for 3000 miles in Argentina and sure enough, I consistently got better mileage on the mid grade. There are various degrees of preignition. It can be much more subtle than audible pinging. Though smaller amounts of preignition won't necessarily damage your engine, they won't help your gas mileage either.
I do too, and here's another weird thing, I get worse on premimum than on mid grade...I assume because I live at a high altitude. And i have heard at higher altitudes it is a waste to even buy permium gas.