I drive like you but i also have the JMS Pedal Max and i like to take off fast and drag race especially with my Mustang.I have a '22 Big Bend and I drive an average of around 31 miles per day. Two thirds of my daily mileage is highway. I run 93 octane fuel. I am not a drive it easy or an every light is a drag race driver. I like to get to speed quickly and settle in. I have 235/60R18 Continental tires. I don't do hand calculations. The mpg on the dash is close enough for as much as I care. And it shows 28.4-28.6.
We recently took a trip from the Rochester NY area down to Legoland in Goshen. I reset trip 2 when I fueled up. Most of the trip was highway at 73-74 mph through the hills of Central NY, North Eastern PA and the Catskill Mountains. On the way down I started around 32-33 indicated, but by the time I drove home we were right back at the same 28.5 I see most of the time.