Back in the 1950’s engineers were touting nuclear powered cards that would run for decades. But imagine the mess a collision would make.
In all seriousness it seems like a Sterling cycle engine would work well in a hybrid. The Swedish make a diesel submarine running a (very) quiet Sterling engine to recharge the batteries. It’s extremely efficient.
Is there some reason we don’t see the Sterling set-up on cars and trucks?
Why would you want an external combustion engine in a car?