Help me settle a bet

I don't have the published article you seek but know that there's a difference between the % of energy that is fully burned and the % of power you extract from doing so. Somewhat like the incandescent light bulb's % of energy used to make light vs what makes heat - a crime!

My best guess is right about now the internal combustion engine is "extracting" about 50-60% at best of available horse power of "burning" fossile fuel. The rest is in fact wasted to heat, friction. Incomplete burning right now is pretty low as you indicated.

IMO - the most waste that could still be captured with techno advances is the wasted heat out a tailpipe. You don't hear much about that??

Just a wild thought I've always had is what if we could capture the waste heat to create steam from a minimal amount of water for example to turn a turbine mmaking something we could use on demand later - electricity or something other than watching it go right out the pipe!

So, IMO you are both about right depending on just how you look at it. We are getting about 99+% of available energy but not all is for powering a vehicle if that's the example.

I seriously don't think oil company conspiracy is involved at all! They'd just love it if more efficient engines were produced because again IMO the nature of people would be to use it up for bigger and better vehicles of all types with lighter engines getting more bang for the buck - a win, win for all,

T