A lot of variables determine the gas mileage in our T4rs. Driving style is a big one. I get about a mile per gallon less than my wife. Her driving style is just better for mileage. Also, driving 65 instead of 70 is 2 mpg. I can toll a popup trailer at 65-70 and get the same gas mileage on the same road driving without it at 80 mph. Other variables: Seasons of the year (temperature) 2-3 mpg, Hills vs flat 2-3 mpg, tires and lift 1-4 mpg, city vs highway, brake calipers sticking, and a few other variables I'm sure I forgot.
Also, subtract about 2 mpg off of what the computer is showing. And, reset it since you are now driving it. It is inaccurate for your driving style.