What is your avg econ????

[Orbital H2]

YOu can manually reset it by paging to that display then holding down the return button. as far as I can tell it does a running average e.g. it calculated the average based on a certian number of data points (mostlikely limited by memory in the computer) and averages in the new data as it is recieved.
For example it might use a 16 point running average where it sums the mileage for the 16 points including the new data then divides by 16. that number could be 16000 for that matter. thats why you will see the average change rapidly immediately after resetting it and it will slow its change after it has been collecting data for a longer period of time.
The data point are based on fuel flow and distance driven. both which are measured by the computer and used for many of the functions that you have on the rig. in the olden days the instantaineous mileage was based on engine vacuum once teh sensor was calibrated to the vehicle.