Nothing against the first law of thermodynamics, but I'd propose that it was more the 'conservation of money', than the 'conservation of energy', which "killed the electric car". Just wanted to point out the obvious, given that probably most here saw the movie.
At that time, car manufacturers where unwilling to finance the continued development of EVs all by themselves (except perhaps in the lab, as Nissan did for battery development), and found a way out of it. Of course the then current state of battery technology made it difficult, but why would a society shy away from this difficulty? The constant improvement of battery technology was already apparent. Ironically it is being pointed out, all the time, that Tesla as a company is not yet making profit. However, the best I know, Tesla is the primary company demonstrating the real-world possibility of building and selling highway capable ("real") electric cars ..... with profit.
And they demonstrated this as a start-up. Companies like GM, Toyota, or Ford, should have been able to do so easier and sooner... if the actual reason had been the battery technology itself, as it becomes convenient to say nowadays.
Perhaps, the insight that electric cars can be desirable even with home charging only (without a charging infrastructure), was necessary for Tesla to get to this point. However, that point is now (more or less) history, and I believe the next thing to demonstrate is that a working infrastructure can be done, in the real world, as well. And implicitly, to demonstrate that EVs are not a niche product by nature. In the US, it seems that the Leaf with a range of 70-100 miles and 50 kW charging isn't completely convincing yet (in regard to this second step), but the Model S will likely make that point, and even if not, it won't be far. After that, it will be primarily about reducing cost for a wider market share, while the Model S will already make profit.
Many EV critics appear to have doubts that it will... and to me, that confirms the point above.
At the same time, another factor is that solar energy is now getting closer to grid parity (being profitable enough), and that adds a lot of enthusiasm to the equation.