The FFH has a bar graph that you can display in the dash that shows MPG over a 10, 20, or 60 minute period. There are 10 bars so each bar is the average mpg over a period of 1, 2, or 6 minutes:Each bar shows mpg over a 6 minute period

During a recent 600 mile trip to Maine I realized that this gauge is not as useful as it could be. It frequently happens that there is a bar that has a very low mpg next to a bar with very high mpg. Imagine the bar graph is set for 10 minutes (so each bar shows mpg during a minute) and the time period for a bar is just beginning. You happen to be gliding the car in EV mode 50 feet to a stop at a traffic light. Say this takes 15 seconds. Then you wait at the light for 45 seconds. The bar appears and its over 60 mpg because you were in EV mode or stopped for the whole minute. Yeah! Then you accelerate from the light and head up a hill for a minute, going 1/2 mile. The next bar comes up and the mileage is dismal - 20 mpg. Looking at the bars, you think that's ok - after all, you have one 60 mpg bar next to the 20 mpg bar, the average of those two must be pretty good!

But its not, you only went 50 feet during the first bar's time period. Since mpg is calculated by dividing miles traveled by gallons used, the overall mpg of those 2 minutes is 20.15 mpg. The appearance of the bars suggests that you should weight each bar equally, but you should not.

I would love to have the option to display a bar graph based on MPG per *mile *traveled, rather than per *minute* traveled. That would be much more useful. Each bar would indicate the mpg over a given distance, say 1, 2, or 5 miles. Each bar would be directly comparable. You could look at the graph and visually get an idea of your recent mpg by looking at the bar heights. You would also be able to directly map the bar heights to mileage along your route - eg a low bar might indicate an uphill climb on your commute.