I'm reposting my comment from
ABG, on a thread about Edison2 using ice to cool the passenger cabins:
Here's another angle that I have not seen mentioned yet: it would be best for efficiency if a car was designed to try and avoid the need for A/C altogether, I think? Thinks like thermal insulation, vigorous passive ventilation, low-e coating on the windows, mesh seats (which weigh less and take less space as well) to let the air circulate *all* around the passengers, and passive evaporative cooling (of water, not ice) -- would go a very long way to solving this, without "costing" much efficiency.
After that, if more cooling is needed, then how about regenerative cooling, that would only run the A/C when slowing the vehicle down, or at least not when accelerating or climbing a hill.
...or, dare I say it, we learn to accept a little sweat? We are talking about a car, after all, that is a tool to transport us over great distances with very little effort from us, so if circumstances are such that we get a little hotter than we'd like, we sweat; just like our bodies are evolved to do!