Having spent much of the past few years working with battery technology investments, I'm not at all clear that the overall environmental impact of hybrids is particularly favorable. Both the battery technology and the associated wire plant are heavily dependent on large quantities of metals such as Copper and Lithium for their construction, with the associated mining/smelting pollution. Assuming one still owns the vehicle around the 8 year mark, the battery plant will need replacement, which is estimated to run about $11K. I foresee a large number of hybrids or their batteries rotting away in dumps (yes, I know that's not the authorized disposal method).

(I won't even get into the safety considerations of crash rescue in the middle of high-voltage wiring and KOH electrolyte. Eeew.)

If anyone concerned about fuel economy and pollution hasn't driven something from the latest crop of diesels, do yourself a favor and check them out. These are not your father's engines. An E320 CDI does 0-60 in 6.8 seconds and generates 500Nm (369 lb-ft) of torque at 1800 RPM with EPA numbers of 27/37 mpg. And that's on a very heavy sedan. I have friends with Jetta TDIs currently getting 55 mpg.

Plug the gas and diesel versions of any car (that has both) into that calculator and you'll see what I mean. The diesel versions consistently generate 2000 fewer pounds of CO2 per year, assuming 10,000 miles driven. They also likely won't kill you if you happen to be locked in the garage with the engine running. The CO emissions are FAR below those of gasoline engines, due to more complete combustion.

I'm of the contention that a rational man can choose a diesel, burn dinosaurs in it, and reasonably conclude he is a better environmental citizen than a driver of either a gasoline-only or a gas hybrid vehicle. (Lest any of the science-impaired go on about particulates, I humbly submit that forest fires generate more of those than diesels ever will.)