Most people don't worry so much about thermal efficiency and care more about cost per mile..

If I could buy a type of vehicle that was only 10% thermally efficient but the fuel was practically free, that would be pretty cost effective even if not thermally efficient.

Even it's 100% coal the EV's are generally better. But it's close enough to equal that you can bias the comparison either way through vehicle choice. The standard mechanism was to choose one of those horribly inefficient compliance vehicles manufacturers created by putting an electric engine in a gas car frame. "It's a fair comparison because it's the same car". Choosing an EV 1000 pounds heavier than a purpose built EV will make the gas car look good.