I ran a 600 mile trip from Chicago in May to Minnesota to do some fishing. Set cruse control at 70 mph. Averaged 15.3 on 87 octane. Shit if you drive 55 you should get 17 or more maybe. I can't drive 55 I would die of boredom. I usually cruse 80 and get a little over 13. It all depends on elevation, temp, flat, mountain roads, what kind of tires different brands weigh more or less, chase racks, bumpers and octane ext. I run method 17 and they are lighter then stock also a back flip. I'm not going to say its a huge improvement but I did notice a little bit of gain in mpg.