Good points, and my concerns are about the labeling, not the cars in general. I do think plug-in hybrids are a great idea, especially if the electricity is derived from renewable resources. However, the labeling of e.g. 100 MPG for a plug in hybrid is, well, maybe not wrong, but it's not strictly correct either. While it is accurate - strictly speaking, that a plug in hybrid may cover the first 100 miles with only one gallon of gas (and thus truly get 100 MPG in terms of gas usage), thereafter mileage (in terms of gas usage) will go down to the non-EV mileage, unless you plug it in before continuing the drive. The issue of how much energy is needed for EV ops aside, if you go on a day-long drive and cover e.g. 800 miles without stopping for re-charge, for the first 100 miles you might get 100 MPG, thereafter if it's a Prius II on a highway, you might get 45 MPG. My concern is that in terms of MPG, the mileage these plug-ins might get is a function of how far you drive them: the further (in one session), the lower your mileage. That's why I think it might be better to label them as e.g. 50 MPG +100 EV miles per trip.

In terms of overall efficiency (not gasoline based efficiency) another way of labeling might be needed. for example, one Gallon of gas could be converted to the equivalent kWh, and combined with the battery capacity. One problem is that the conversion of one gallon of gas to a kWh equivalent would depend on the efficiency of the drive train, and is obviously not a constant.

Aaarrrgghhh, our technology is advancing faster than our terminology!



M