A6. Regular unleaded petroleum
has an octane rating of 87; E85 has an octane rating
ranging from 100-105 that provides for superior engine
performance. For example, Saab FFV engines produce
20% more power when using E85 fuel than their standard
petrol engines.
Regular unleaded petroleum also has a large number
of impurities in it which ultimately lead to coking
up and disintegration of engine parts. Fuel Ethanol
is a very pure (99.8%) fuel which does not have
these impurities so it should be better for your
engine over the long term.