I agree with the general theme that hybrids like the Prius are pretty xexexexe - the mpg isn't significantly more than some of the newer petrol- or diesel-only cars and so doesn't warrant the additional costs, IMO.
The worry I have when we talk about electric, hydrogen or biofuel cars is that the basic laws of physics seem to be being overlooked slightly. You can't make energy from nothing - electricity & hydrogen might be non-polluting but how much energy do you have to put in to create it and transport it to where it is needed? If the generation-energy could come from natural, sustainable sources then that's great - but we are already having difficulty coming up with power sources to run our homes and businesses, so if we also require that cars also swap over to these new fuels now many more nuclear reactors of wind/solar farms will we need to build and how much energy is needed to create those?
Biofuels really worry me as, at the moment, huge swathes of agricultural land (once used for food crops or just boring old tropical rainforest) are being turned over to producing what I think are ethically rather dodgy biofuels. We have already seen the price of basic staples like rice soaring and I fear that yet more third-world countries will go for the biofuel cash-crop rather than grow the food their people need. Current biofuels seem destined to escalate the destruction of the rainforests and raise the price of basic foods. Only the recent research into algal biofuels seems to show a possible way forward.
Anyway, I'm not saying that fossil fuels are not a problem - but, as someone else said, the best thing we could do is to reduce our consumption of fuels while improving the efficiency of our homes, vehicles and power plants.
