The old dream meter......makes people who are lazy about old fashioned math feel better about their purchase.Yea, rarely perfectly accurate, and usually sway to the better side of mpg’s…but they are usually within the “ballpark”. I did a year long side by side calculation test on one of my rams…the computer was notoriously off about a mile per gallon (on the better side) vs the actual mileage/gallonage calculation, which is what the year long average off was. They are only so accurate. Close, but not perfect.