You are obviously wrong, either by not paying attention to the teacher, or by being lied to by the teacher...
Ethanol + air mixtures burns slower than normal gasoline + air. It's also much more simpler composed than gasoline, that has hundreds of different carbon-based
chemical molecules. Ethanol combustion is more consistent and "predictable" than gasoline ditto. An engine run at pure ethanol produces virtually no soot, since all
molecules react at the same temperature, whereas even stociometric gasoline combustion will emit unburnt carbon based residues.
(Something that the cat has to oxidize later.) Gasoline is also much more prone to knocking and "pingin"(?), due to uneven combustion.
The volumetric energy content is less in ethanol, so you need more E85 than gasoline to move your car a certain distance.
The octane rating is much higher in ethanol, which allows you to run higher compression ratio (modify engine), which increases power and fuel efficiency.
MOST IMPORTANT: gasoline is fossilized carbons = contributes to global warming.
Ethanol can be made of "green carbon" = NO or very little contribution to global warming.
NB! Already by mixing 5 or 10% ethanol in the gasoline you will increase power, fuel efficiency (due to synergetic effects) and reduce global warming effects!
/Alexander - who prefers facts, not urban myths