Energy efficiency Bizzaro world

Someone is going to send someone to kill me for this kind of blogging especially if it come to be any more than obscure.
So i know a few things about thermodynamics. It is not all visible and easy to see, but most of us don't know, but would give a hoot if we did.
We simply accept that 2/3 of all energy is "junked" while we drive around. All fuel powered engines are this way. We make no attempt to use our abilities to try to captur the waste heat produced and turn it into motive power.
We do the something very similar with power production.
Here's the problem, and it is entirely a human communication problem. It is similar to the belief that the Pope stand between you and God. This is simply not so.
We have all heard the urban myth of much higher efficienc in fuel engines, but no one seems to be able to make it not a myth even though that it is possible to capture and use the eshaust heat which apparently has 2 times as much energy than the internal combustion aspect of the output engine.
I feel as if i can change all that with logic.
Here is how it goes. There are two kinds of heat capture engines that come to mind.
One is to use compressed pnumatic drive and heat the air with exhaust generated heat.
The second is to create an effective boiler near the exhaust manifold collecting that extremely high heat and pushing it through engine block and crankshaft integrated two stroke steam engine.
It is not as if these idea are super simple, but they are not hard to conceive and would be easy enough to improve upon once built.
I guess i will have to go into it. I swear there is nobody and no one other than oil execs who know this an want to stifle it.
Let's say everyone could use about half as much fuel easily, using some modified "hardware"