>>fooker+D6
The following link has some charts for just the ethanol. They look about as expected. Some things get better the more ethanol you use, some get diminishing returns, some have an inflection point and get worse, some are just worse as you increase ethanol percentage.

https://www.researchgate.net/profile/Aimen-Zeiny/publication...

>>aitchn+Rr
It does not. Flex fuel cars are widely used South America, especially Brazil where Ethanol is more available than gas. In North America or Europe it depends. Sometimes it is available directly from OEM, sometimes you need aftermarket modification to add Ethanol sensor to run engine with correct lambda.

Here you have list of Flex Fuel cars - cars which has Ethanol sensor and are able to run on gas or Ethanol.

https://en.wikipedia.org/wiki/List_of_flexible-fuel_vehicles...