Although it's been used for a fairly wide array of algorithms for decades. Everything from alpha-beta tree search to k-nearest-neighbors to decision forests to neural nets are considered AI.
Edit: The paper is called
Avoiding fusion plasma tearing instability with deep reinforcement learning
Reinforcement learning and deep neural nets are buzzwordy these days, but neural nets have been an AI thing for decades and decades.
Yeah. Power plants are nowhere near 90% efficient.
It's worth emphasizing, though, that they're still way, way more efficient than car engines are.
Also, regenerative breaking saves a lot of energy. Basically, instead of using the motor to increase the cars speed, you use it as a generator to recharge the battery.