So about those plug in hybrids

So with January already being the snowiest winter of record and this winter well on it's way to be the wettest ever, you do wonder what the global-warming crowd has to say now.
Now I know that the whole discussion becomes one about global weirding not warming but as I prepare to spend another weekend digging out my hybrid car I really wonder if this wasn't some kind of scam perpetuated by the manufactures of those funny hybrid batteries.

Now I got into a discussion with a guy last week who told me that my carbon-footprint with the hybrid was actually greater than it would have been if I bought an F150. To me the issue has never really been about global-warming as much as it is depending on a limited resource, especially one harvested mainly by oligarchies who hate us. I want to get off fossil fuels to starve the beast.
Now what I've never quite understood is how they will figure out true gas mileage for plug-in hybrids. In the case of my hybrid the battery charges from the engine so all the energy it takes is still from gasoline, but a plug-in hybrid will get a substantial amount of it's energy from the grid.
Now does this mean the VOLT will have a miles per kilowatt rating or will there be some complicated conversion that nobody can quite understand sort of like the QB ratings?
But really since a huge amount of the energy which comes from the grid was derived from coal will a plug-in hybrid actually indirectly cause more smog than a standard gasoline car? Although I guess West Virginia doesn't officially hate us... well maybe some of us.
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