[atomicradish]

In advance, sorry if this should go under "Instrumentation" but that forum looked completely dead.

So I just bought a ScanGauge for my Honda Accord and I had used it for the "Daily" MPG tracking features prior to first fillup, and it seemed consistent with results I had previously been getting without instrumentation. Today I filled up the tank completely and followed the instructions for calibrating the device to a full tank of gas. I also reset my trip meter since I've noticed the SG does not recognize coasting with the engine off.

One shift of food delivery with Uber Eats runs me 52.0 miles. I ecodrove the hell out of that car, especially considering that I was also working. SG reports 31.5 MPG for the tank which is slightly above average for me, but I figured it was pretty accurate now that I can monitor the MPG in real time.

So I go back to the same gas station, same exact pump, and somehow the car manages to take 3.43 gallons to fillup. Barely 15 MPG.

The numbers make zero sense to me, can someone explain what might have happened? I filled to the first "click" each time as SG instructions say plus I really don't want to screw up the EVAP system. I don't think its possible to have gotten 15 MPG.