This is not investing, you're speculating.
SIDE NOTE:
It's absolutely mind boggling that the American public is now ramping up their purchases of larger trucks and SUVs because gas prices have dropped. Wait! Not so mind boggling at all. :) Were pretty stupid
People choosing what vehicle they want to drive is each person's rational choice, made through the exercise of free will based upon an assessment of their own self interest. I'm not smart or cocky enough to make those choices for anybody other than myself. Some of those choices may be enlightened and wise, and others not so, based upon point of view. But it is not my role to judge. And I don't want to live in a society where somebody else, typically through governmental action, limits my choices.
No free lunch. Hybrids contain batteries that pose disposal issues. Electric vehicles are powered by the grid. And on and on and on.
I think it is wonderful that gas prices have dropped, thanks to the spouting plethora of energy created by the U.S. private sector, not the government. The "Peak Oil" crowd has certainly been put at bay, and lower energy prices provide Americans with an effective tax break. Energy prices are regressive, too, so the current scenario is preferentially helping the poor.