I don't place much worth on my computed mileage at the pump. This is because I have no way of determining the accuracy of each fill. Unless I fill the tank to the point of overflowing, there is no way of knowing how full I filled each tank. I could be off by as much as a gallon. I notice on extremely hot days the gas pump kicks off prematurely (especially when riding on fumes). I have found my computed mileage to be pretty close to the display mileage. Any differences I attributed to my poor pump filling skills.

 

Actually, on most of my tanks I HAVE filled to the filler neck... just to make sure of the accuracy of this calculation (and to get another 100 miles per tank!). The result is always the same.

Incidentally, I've always found that I pump in between 1.8 and 2.0 gallons after the pump first clicks off (to get it to the filler neck). Since that proved to be very accurate over the first 10 tanks, I've backed off a bit and now only add 1.0 gallons after first click. That way I still get the extended range, but no worries about spilling anything nor possible contamination of the evaporative components of the fuel system.

 

Thanks all,

I think we have established that actual mpg is about 2-4% better than displayed, on the HCHII.