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The Gen2 Volt is rated at 106 MPGe. Based on VoltStats.net, there are plenty of people getting much better than that, but the note at the bottom of that website says that they cannot accurately calculate it. The formula they list is:

Total Miles / (Gallons Burned + (EV Miles / EPA rating))


Is [Total Miles] equal to the odometer reading? I can't remember off hand, but does the Volt display show the total EV-only miles?

Is there a simpler way to calculate this? For example, the rated EV range is 53 miles and MPGe is 106. If I've achieved 67 EV range, is it accurate to say that my MPGe is 134? Or are those not that closely related?
 

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The formula they list is:

Total Miles / (Gallons Burned + (EV Miles / EPA rating))
See this Wikipedia article for the full formula, which is based not just on how much gas was burned but also how much electricity you pulled out of the wall outlet in order to charge the battery. If you're only looking at the efficiency of the gas engine itself, you just use "MPG" (miles divided by gallons), "MPGe" doesn't enter into it. "MPGe" only exists to compare the efficiency of vehicles that use different fuel sources, and for the Volt that means gas and electricity.
 

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The Gen2 Volt is rated at 106 MPGe. Based on VoltStats.net, there are plenty of people getting much better than that, but the note at the bottom of that website says that they cannot accurately calculate it.
I count only 7 vehicles on Voltstats that are showing MPGe values greater than their model year's EPA electric efficiency rating, and all 7 of those vehicles are reporting unrealistically high MPG_cs values -- all above 100 MPG_cs. (One is as high as 2,323 MPG.) That tells me that there's either an error in the OnStar data from those vehicles (which definitely happens occasionally), or those owners are skewing the data somehow -- maybe switching to only Hold Mode during long descents, or something weird like that.

Is there a simpler way to calculate this? For example, the rated EV range is 53 miles and MPGe is 106. If I've achieved 67 EV range, is it accurate to say that my MPGe is 134? Or are those not that closely related?
Yes, roughly. Your precise efficiency would depend on other factors, like whether your EVSE is L1 or L2, environmental conditions (namely temperature) during charging, etc. But in order to determine miles per full charge, Voltstats would also need to be able to pull a vehicles charging history from OnStar, which I don't think it can do.
 

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The problem is that VoltStats doesn't have access to how many kWh were used for that 38, 53, 67 EV miles, etc. So it has to simply assume the EPA's MPGe rating of the car for those EV miles when it calculates overall MPGe for electric + gas.

I don't think Voltstats.net is accurate at all for MPGe.
The energy use screen on the center display shows the car's lifetime MPGe. Mine is at 115, but Voltstat.net has it as 97.
See above for why VoltStats.net MPGe calculation will be lower. The OnStar data they have access to doesn't include kWh used.
 

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My MPGe is 168

Think I am getting better than the posted MPGe. Here is my drive today, I am getting about 168 MPGe.

Photo is in metric, equates to 168
 

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The MPGe calculation gives me a headache.... What I check regularly is on the Leaf screen: Miles, E and G, gallons and Kwh. For Gen2 I expect 41-45 mpg and 4.5 or more mi/kwh. MPGe was created, I believe, for new car buyers to quickly compare many makes of cars, but after the sale, the stat is, for me, useless.
 

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The MPGe EPA rating is for electric use only. The MPGe on Voltstats is a blended number, not electric only. They are calculating two different things.

The typical Volt driver on Voltstats with a high MPGe, usually achieves that by driving mostly on electric. If you look, it's almost always in the high 90% range. Then the blended result will be close to the EPA MPGe rating, cause the ICE use drags the average down. Less ICE, the higher the MPGe.

For the OP's intents and purposes, the MPGe showing on the DIC is comparable to the MPGe the EPA uses. So, his example of 67mile range and 134MPGe is an accurate comparison to the EPA's 106MPGe. It's an apples to apples comparison. It's an apples to oranges comparison when you look at Voltstats.
 
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