Research is such, that we are mostly running our engines with the science of the 40's.
At the introduction of multi-valve in cars engines and turbos in tractors on the common market, I had to laugh hard, for this was tested and manufactured to death already inWW2. No new invention. But since economy did not demand it (that is, as well, OIL economy), it was not so much needed.
Remember the 70's oil price jump, - suddenly jap cars hat used very little fuel were the biggest in increase.
It's the money. And the money you burn while driving is oil money.
The bosses of oil money are not so many, and they don't like changes that could make their money less just like that.
There are many little inventions somewhere, which all could lower fossile fuel burns . Somehow they lag a little.
There are also alternative energy sources....same story.
While there are indeed many possibilities of both alternative energy and energy saving, they both lack the power as a whole of a big big oil tycoon as well as while the oil price is lower, they are in the lower end of competition.
So, oil power is going to keep them as far down as possible, - it is a conflict that will end...where?