I get that Elite, and I agree that there is a substantial carbon footprint to the production of batteries and the charging of electric vehicles overall, but we would be talking about thousands of TDis running around with tons of added emissions being produced, just to save a few MPG (a 7mpg saving is VERY optimistic, and the added power is a completely separate issue IMHO). It's apples to oranges, anyway because you still have to factor in the carbon footprint from the production of the Diesel fuel in the first place, which I would think is substantially more than what is required to produce the added electricity needed to charge a like number of electric vehicles and to produce the batteries for them. And of, course, an electric vehicle has almost a zero carbon footprint in operation, so it offsets.
Sorry this is so far off of your original topic, but I too often wonder if electric vehicles even make sense in this regard. You can make the same argument against Hydrogen or LPG I guess...