From what I understand they have cures for diseases, but big pharma companies bought up some of the patents. Just like the oil companies bought up patents ever since the 1920's that would have improved gas mileage. I saw a list of these that someone posted a while back. Don't know if I can find it.
All those 100 mile per gallon carburetor stories
are pure fairy tales
Even with strict computer controlled tuning
and laboratory grade electronic fuel injection
that's standard on new vehicles now ( science
fiction back in the 60's) you're not going
to get 100 miles a gallon out of a 1/2 ton truck
or full size sedan . None of the experimental
vehicles they show on these scientific documentaries
are pulling an air conditioning compressor, or
a high amperage alternator, or a power steering
pump or any engine driven accessories.
Lots of factors in the real world
Fuel formulations, road drag/ rolling resistance,
wind resistance, pavement variations, etc. etc.