Could you please elaborate. I'd really appreciate to understand at what intervals do you shift at XD

 

I don't stick to shift intervals as I like to drive hard when I'm shifting through gears. If you want the best mileage then keep the RPMs as low as possible, but then I ask why bother with this car, this engine etc? If all you want is gas mileage keep the RPMs under 3k all the time unless you are in 5th gear and never stomp on the gas. Personally, I'd be bored out of my skull in the first 1/8 tank of gas but you will notice the gas mileage bump.

And if you are getting only 20-22 mpg, you might want to look at a tune up. Air filter, fuel filter, spark plugs, coolant temp sensor, etc.

And be sure you are calculating your MPG considering your tire size. If you have changed tire size from standard then your speedometer and odometer are off as well as the heads up display readings for MPG. You need to adjust your calcs accordingly. Do a search for tire size calc and you will find the thread with a link to a tire size calculator. Or set the cruise and time yourself between mile markers on the highway.

80mph = 45 second mile
75mph = 48 second mile
60mph = 60 second mile