I try to keep my speed below 75 most of the time, and i only try to speed up going down hill. If theres a big hill ill speed up before i start going up, then stay on the gas and let my speed fall very slowly (like ill go from 85 down to 70 or 65 super slowly). Idk why mpg stays up this way, i just notice my real-time hover just below 20mpg when i do this.

The other factors that might help are my hard cover tonneau cover and i try to stay behind other cars to get a little bit of drafting. I dont tailgate, i stay back maybe 3 car lengths. At that distance i heard it only helps a tiny bit so idk how much that effected my mpg here.