The Inventor assumed they would use it & didn’t ask or know about performance clauses & therefore it was shelved.
Dear Inventor X,
I don't believe Detroit pays for technology and doesn't use it.
Back in the 70's the rumors of 75mpg carburetors were rampant.
My Uncle was a plant manager for Chrysler. I asked him why don't you guys sell cars with the 75 mpg carburetors?
His answer was so simple. "Terry if we had something like that we could sell so many Chrysler would be number one."
Let's say Detroit did shelve 100mpg technology. It would be hard to keep a secret.
Come to grips with this fact. All patents expire and are available to the public.
I will believe you about the 1940's 100mpg patent when I see it.
If it does exist you should be able to come up with a patent number.