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MPGe Question - Why So Little $$$ Savings In Huge MPGe vs MPG difference

jsurpless 4 years ago • updated 4 years ago • 1

I realize that the MPGe calculation is based on the energy equivalent of kWh vs a gallon of gas and that it is settable in the TeslaFi settings page.

So I understand that my most recent drive of 8.56 miles that used 2.69 kWh did so at 314 Wh/mile and that this translates to to 107.2 MPGe.  Similarly, if my electrical rate is $ 0.25 per kWh, this translates to a cost of $0.67 for that drive.  

Now, if I had driven my old gas car that had ~30 MPG, I'd have used ~0.285 gallons of gas which would have cost me $0.85.

What I am struggling with is the relatively negligible savings in the EV vs the ICE car, despite the more than 3x "MPG" difference.  What am I not understanding?

jsurpless 4 years ago

Well, I feel silly - I thought about it more after posting this and I suddenly realized the answer to my question.

There is a 3x "MPG" comparison but I failed to consider that my "gas" now costs nearly 3x as much as before.

Still saving $$$ but the MPGe rating is really misleading because it doesn't consider the cost of the fuel.

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