We used our ScanGauge-D on our first long trip over the 4th of July weekend towing our 8k# tandem enclosed. We averaged about 8.3mpg (according to the unit) in the hills of Kentucky. At about 380mi on the trip, my low fuel light came on.
My ScanGauge said I'd only used 39 gal. (This seemed around consistent with what I had seen out of our Seneca in the past for indicating low fuel and still having plenty). I went ahead and drove it on up to 490 mi on the trip.
We used the genset heavily that weekend and while moving so I was a bit cautious of going much over what the scangauge said we used as I had no definitive way of 1) knowing how much the onan gulped down 2) my pre-trip fillup was at a passenger filling station and I had to turn the rig around to get the driver's tank filled; so some self-balancing occurred while I turned around. (it said 59 gal used when we finally stopped).
When it was all said and done, I filled 64 gal into the tank. For the last 50 -75 mi, the in-dash gauge was buried on E (really unnerving). I cannot explain how much I despise a gauge that's so inaccurate.
'14 Jayco Seneca 37fs
20' Look Enclosed Trailer