“...even when emissions from generating the electricity are taken into account, electric vehicles have a much smaller carbon footprint than gas-powered vehicles because they are much more efficient.”
Carbon dioxide emissions (not that they really matter) and energy efficiency are two different (if related) things.
Internal combustion engines are (if I remember correctly) about 30% efficient, maybe a bit better if running close to their thermodynamic ideal. Using electric energy to power a drive train is, in fact, a lot more efficient, in terms of the fraction of the total energy that ends up moving the vehicle (somewhere in the neighborhood of 80%, if I remember correctly).
BUT the energy in the battery doesn’t magically appear there - it has to be generated somewhere. If it comes from a coal-fired plant (our most common generation source), you’re talking somewhere in the neighborhood of 60 to 70% energy wasted in generation losses and transmission losses, which wipes out the benefits described above.
Now if you’re getting your electrons from nukes, it’s a different story - no greenhouse gases, little generation loss, mostly just transmission losses.
But I don’t think people pushing electric cars are going to lobby for a whole bunch of new nuclear plants.
I use recycled electrons, regardless.