Even when an EV is powered entirely by coal power, it's still on par with a decent gasoline vehicle. Add any other power to the mix (it's rare to have a power grid that's exclusively coal) and you do better than traditional cars, even when said traditional cars aren't gaming the system.

We can probably be confident that power plants aren't cheating, because they're so few in number and are therefore much easier to monitor. And we can be highly confident that solar, wind, nuclear, hydro, etc. aren't lying about their emissions.

Don't forget lithium mining, processing, and battery creation/disposal.

It depends on a lot of things: power source, location, etc…

But it’s certainly easier to monitor a few thousand smokestacks than 200 million cars.