Fuel range seems to vary pretty significantly when driving. Does anyone know how the figure is calculated?

 

Your current AVERAGE miles per gallon from computer & how many gallons remain in the tank at the present time.

 

I believe it has to do with throttle position and R.P.M in addition to barrys explanation... I notice when I have my foot out of the throttle and or coasting down hill the range increases greatly.... When my foot is in it and at higher than normal crusing speed the opposite happens.....

 

Possibly but I think it would be the current mpg x the number of gallons of fuel left. When I say current mpg, I mean the instant mpg which unfortunately is not something I can see in the display.