For the last month I've been running 93oct vs 89oct. I also replaced my stock air filter with a K&N drop in. During my 85 mile daily commute (60-75mph on hwy and some stop and go traffic) my avg economy went from 34-35mpg to 37-38mpg and now getting over 500miles of range on a tank. Not to bad. Usually have 40psi in the tires also. I'll be ordering the trifecta tune so maybe it will increase slightly more.