I have never gotten better than 15 so I think you guys getting 16.4 have magic raptors. I can only get 91 octane maybe thats why.
15-16 mpg is not unusual at all in my SCAB with 91 octane (no ethanol). Although I have pulled off 17+ on a couple tanks and one was with mostly like up to 10% ethanol. I think the fun part is I can get 14-15 mpg easily off-road when I'm just "cruising" dirt trails at 50-80 mph. The truck computer actually underestimates my mileage usually. I fill up and do the math all the time. I don't drive it like a race car on road though (not yet at least lol!).