Here is one. My Porsche has a display which tells you the MPG. However the car display is consistently between 1 and 2 mpg better than what I calculate after filling the tank and doing the math. And I repeat it's consistently worse than the display which calculates the mgp per tankful which is probably what most people rely on. I've been meaning to bring this up with the dealer but haven't so far. This is in addition to not coming anywhere near to the stated MPG and with conservative driving (non sport mode ..)