So when you guys talk about the mpg you're getting, are you just bringing up the instant economy screen on the DIC (the one that pretty much constantly fluctuates from like 5 to 100 depending on if you're accelerating or coasting) and just taking the reading while cruising at a certain speed, or resetting the average economy and waiting a few miles for it to settle down?
I've only reset that once on mine. Right after I got it almost 4 years ago (it said 14.2). It currently, and has been for the past couple years, reading 12.something.
When I reset it, it read pretty high at first, actually for a couple days, up near 20 and the upper teens. Then eventually settle down lower in the 14-16 range, then after a few more days and driving mostly around town goes to the 12-13 range.
When I mention it, it's from watching the Instant MPG gauge while cruising. To determine my highway MPG, I'll average a stretch of uninterrupted cruising of anywhere from a couple of miles to a few dozen miles, depending on interruptions. I rarely drive enough distance on the highway to make resetting and watching the Average MPG gauge an accurate measurement. I did this for my last trip to and from Tampa back in 2020 so I could get the average MPG for the whole trip.
I live about 15 miles from the interstate down a straight 4-lane highway with a 65 MPH speed limit. From where I get on to where I'd turn to go to I-10 is a straight and flat 5-mile stretch with no stops and usually no traffic that affects speed. That's my "test strip". I'll get on that 65 MPH highway, set the cruise on 70 and watch the instant MPG over a few miles to gauge how it's running and/or to know if the gas I just got is crappy, etc. The MPG through town, with the time sitting at traffic lights, creeping through traffic, stop-and-go, etc. is useless info to me. It's gonna be bad no matter what due to the many outside variables.
Other than for road trips, I don't fill up and I don't put in X amount of gallons. I'll put in about what I need for that day's errand(s) and stop at the nearest dollar amount in multiples of five. If I want $20.00 and go over to $20.01, I'm trying for $25.00 next. Anyway, my point is that I can't really hand calculate the average MPG this way. I have before, many times, and it was always really close to what the gauge displayed.