Just read an article in the December issue of Design World - "Series hybrid electric truck".
Seems Wal-Mart is getting into the green thing with a custom built streamlined electric truck with a Capstone micro-turbine generator range extender. Neat looking truck. The steering wheel says "Peterbilt". They also have a special streamlined 53' trailer.
On the third page of the article, they quote "DoT statistics" that show the typical heavy highway hauler gets 5.89 MPG.
On page six they make a big deal about how 50 gallons of Diesel in this thing's tank can be converted to 325 kWh of energy, which can drive the fully loaded truck a whopping (estimated) 217 miles.
A little math: 217 / 50 = 4.34 MPG.
So, for an investment of around $30K for the micro-turbine, and adding the weight and cost of whatever batteries it carries to qualify as a "hybrid", this green wonder gets 73% of the mileage of the conventional Diesel, which, with modern pollution controls, is extremely clean, costs a whole lot less, and uses little in the way of rare earths in its' engine.
Like I keep saying - going "green" for the sake of political correctness is just plain stupid.