[wizard_of-ahs]

I've noticed that most of my info is correct, except for my CS miles...I actually get about 37mpg but voltstats is reporting 75, I WISH! !

 

[wordptom]

I have observed only one difference between a Voltstats number and a dash display, the Lifetime MPG.

I bought my 2012 Volt in April of that year, and about a month later I began keeping daily records of my usage screen readings (finally broke that habit after 3 years!). Throughout the years, the various on-line sources of OnStar-reported stats all showed the same total miles driven and the total electric miles driven, and those numbers mirrored the totals of the numbers I collected daily from my Volt’s own display readings.

However, there have always been discrepancies in Lifetime MPG reporting. At the 20,000 total miles point, for example, I noted that my Lifetime MPG was either 127 (according to my driver’s display, my OnStar app, and myvolt.com), or 124 (according to the voltstats.net website and the VoltDC app).

That difference continues to this day (my car says 131, Voltstats says 129.34). It reflects a total lifetime gas usage difference of ~4 gallons - really not very much in the grand scheme of things - that hasn’t changed since I first noticed it, and appears to date back to an early point in the car’s existence. Was gas put into the tank at the factory for testing, and then the dealer reset the MPG when the car originally arrived at the dealership or when I bought it, so that my car’s display reports data from one point in time, and Voltstats reports it from a slightly earlier point in time?

As for your single trip display/Voltstats differences, I’m not sure if GM programmers were prepared for the complexity of accounting for energy usage in Hold-mode equipped Volts. When in Hold mode, the battery soc may oscillate a bit above and below the Hold set point, and braking regen may put the soc above it. If you switch back to Normal when the soc is above the Hold point, the use of that battery power should be recorded as Gas Miles until the soc drops down to the Hold point.

If you switch from Hold to Normal just as you crest a hill’s summit, and if the soc happens to be above the Hold point at that moment, then downhill regen will just increase the soc, and when you hit the level again, you have even more battery power to use before it drops back to the previously set Hold set point (i.e., perhaps this accounts for the Gas Miles you noticed).

Or perhaps during this particular drive, you switched to Normal and started downhill just as the soc was dropping back down to the Hold set point, and the car display, in effect, remained in Extended Range Mode and recorded the downhill and regen-battery miles as Gas Miles. Doubt if there was enough fuel consumed during the downhill driving to confirm the mode (i.e., kWh or Gas used?). Perhaps the computer, however, had estimated the soc readings as being at the Hold set point and had recorded (and later uploaded via OnStar) the downhill and regen powered distances as Electric Miles.

 

[alfon]

Based on that trip I would rather rely more on the Volt's dash display then Voltstats.net. There is no way that I went 66.7 miles on electric on that trip.