Foggy I actually agree with you! Smaller more efficient engines in my view is the best way to go. All the so called alternatives at this point time are generally impractical.
Cool, I knew you would come to your senses...
If I recall correctly, it takes about 18 HP to keep a full sized car doing about 55 MPH down the highway.
There was a guy I met in Ohio in the early 70's that used a flywheel, that weighed about five hundred pounds (or more) that a small engine ran and kept spinning the flywheel at a high RPM. The engine by itself didn't have the HP to make the car take off and zip up to the speed limit, but the energy stored in this spinning flywheel did. He used a regular Transmission and had a belt drive to it like a snowmachines clutch, the belt would change on the clutches to meet the rpm demand.
To make a long story short, he had a working model in a Cadillac car, and it took off about as fast as a regular car, it just got 80+ miles to the gallon because of the smaller engine. If you were in it, you wouldn't know anything was different other than a bit of a whine from under the hood, but that could have been addressed.
I would assume that if you had to go up long grades, the energy would bleed off the flywheel and you would be down to the twenty HP or so the engine put out, creeping you up over the top of the mountain.
He died shortly after I met him and rode in the car, and never heard anything about it after that.