I have seen this too. After I bought the car, the lifetime avg crept up steadily until it reached 70.2. I've seemed to have peaked there. Sometimes it drops to 70.0 even after a good mpg segment, like it was lagging. It always seems to go back up to 70.2 after a low mpg segment. I realize that as miles accumulate, the lifetime average will change less frequently. However, as the average display has a tenth digit, I feel that the figure does not change or compute finely enough. For instance, I never see 70.1 on my liftime average...it's always 70.0 or 70.2 and occasionally 70.5 and no other numbers in between.