Vapor Carburetors were invented in the 1930's, achieved 200 MPG+, and were installed on Sherman Tanks during WWII to run the German Armored Divisions out of fuel. Pogue Carburetors.
After WW2, this simple technology was deemed "classified" and any innovators that tried to introduce these simple inventions to the public, including Pogue, were threatened and/or murdered (research the Tom Ogle case).
There never was a need for "emissions" equipment on any car or truck engines. At one point, cars were designed that achieved over 500 MPG during the Saudi Oil Embago - but never released.
The US WAR DEPARTMENT knew only vapor burns.
A vapor carburetor is a relatively simple conversion to any gasoline powered vehicle. Surely works for diesel, too. Takes your engine from about 25% efficient to well above 80% efficient.
SUPER CARBURETORS.

https://fuel-efficient-veh...

https://www.youtube.com/wa...

like this. bring it on but i do think gasoline will be in the past at some time.