Can someone explain for me the miles per gallon display on the dashboard. I think the green bar in the back of the display is the miles per gallon that very instant. I think the white line and number is an average miles per gallon that can go up or down as you drive. My question is because I was driving today and it displayed 14.3 then I reset it and it currently leveled out around 20.3. It mistifies my as to why the drastic change after the reset?

 

The MPG is constantly updating as you drive. As you drive it becomes an average over the distance since the last reset. If you reset the display while driving, it will give you a high initial reading of what might be the current mpg the moment of reset. Over a long distance, this reading will gradually decline and normalize as approaches the mpg you may have been showing at the time you reset it.

Recent, I made a 300 mile trip. The mpg average was approx 19mpg. I reset it and it jumped to 21mpg. As I continued to drive after the trip, in town and out of town some, the mpg gradually decreased to approx the same as it was when I reset it. I think it may have ended up being a half mpg higher than at reset.

When I fill the tank, i always reset the MPG screen and Trip A. If I reset the MPG screen before the next fill up, I can compare the mpg from the MPG screen and the trip A. Over time, since I have a 65 gallon tank, they will eventually come close to being the same mpg prior to the next fill up.

The green bars are similar to a vacuum gauge readout on a gasoline engine. On a gasoline engine, the higher the manifold vacuum usually equates to more fuel efficient and higher mpg. Same goes for the green bars on this screen. Not sure how the computer/ECM/PCM computes the bars since a diesel does not have a throttle plate to like a gasoline engine to create manifold vacuum.