Originally Posted by suss6052
As to the avg trip mpg it can't immediately go to where it was before, there is not enough data if you reset it while getting some specific mpg figure, ex. 40 but then you reset it the amount of data stored is zero initially, so it starts off low as it begins to average before converging on the average. That is actually what you'd want to see happen, not it instantly come back with the same number from before. We don't have an instant mpg feedback on the car, so if you're looking for instant data you'd need a scan guage type device.
There is no reason why it cannot refer to the previous results window back in time a bit (that it must have internally) and use that for the starting point of the computation. Ford simply chose not to implement it the way everyone else does.
The way they do it brings into question if the average results are trustworthy at all because at no point in my several mile highway drive was I getting only 25 mpg - so that value should never be figured into the average. Maybe it is not figured in, but I have no way of knowing.