Sometimes, after we have looked at something in a certain way for a really long time, we cannot see it any other way. Then someone with the stuff of genius comes along and reconceptualizes it and we say, "why didn't I think of that!"
Such is the case with the conventional four-stroke internal combustion engine. It's been mass produced, pretty much in exactly the same basic form that we see today, since the Model T Ford started rolling off the assembly line more than a century ago.
Can the internal combustion be made better before it is replaced? If so how? Here is one way to rethink the ICE. It's called the Opposed Piston Opposed Cylinder (OPOC) engine from Ecomotors. "We claim we can get four times the power from the same mass," meaning that the weight of the engine is greatly reduced. Here is a nice explanation of the OPOC engine:
In the video he claims 40% fuel efficiency, which roughly doubles that of a conventional four stroke engine.
Is this the stuff of genius? It is if they can bring it to market and the weight/efficiency claims hold up once it is mass produced.