They take up a lot of space and require a lot more energy to move around. Even if we get 100% electric vehicles with all clean power generation - it's still a massive toll on the environment.
A car isn't a helicopter, they require reasonably good roads with high costs of maintenance(and a lot of other infrastructure to support roads).
Also car dependent lifestyle means that population density drops, with less walkable places than ever.
No it isn't. We just haven't figured it out yet. Those aren't the same thing.