Of course it has an effect. The question is a) how much and b) whether the "solutions" are really much better. In the case of hybrids, I'd say no, but I'm very much in favour of greater research into hydrogen fuel cells.
Not just for cars either. Wind farms and hydroelectricity will never produce enough energy for our needs, and I don't think forcibly lessening our needs would benefit mankind either. However burning coal to generate electricity cannot continue endlessly. Setting aside the impact to global temperature, there's smog, and even more pressing, scarcity.
That to me is the crux of the fossil fuel argument. It shouldn't be about whether the planet is warming (which it is) or whether CO2 has any impact (which it clearly does) or even about how much (where I think there is probably some genuine debate). We're running out of fossil fuels, and eventually we'll have to find alternative energy sources, not because of global warming, but because of scarcity.