WHOO BOY!! You can rant about higher octane gas but there are some things about
higher octane that you are misunderstanding. Higher octane fuel blends are basically
better for high compression engines because they tend to prevent pre-ignition.
Premium grade and the lower grades of gas all have the same thermal energy, though
I highly suspect that ethanol blends would be lower.
BTW, there were different grades of gas before ethanol was ever introduced, so that is
not the reason for differences in gasoline grades.
Here is some information to help clear up the misconceptions about the difference between
premium and lower grades of gasoline.
http://engineering.mit.edu/ask/what%...gular-gasoline
Note near the bottom of this item here that there are different methods for determining
octane numbers. So a 91 octane rating in some country would be equivalent to 87 in the
US and Canada.
https://en.wikipedia.org/wiki/Octane_rating
Given that the Chinese are not the best at clarifying things, (service manual anyone? -
kilometers or miles on the speedo gauge? recording distance in miles or km?) it may be
hard to tell which method of octane rating they are using for the recommendation. That
is, unless it specifically gives the rating method used for that recommended fuel. If it is
not specifically given, I would wonder what the octane rating method is used in the country
of manufacture.
So if you can get by with the less expensive grades without pre-ignition problems, then
it would make sense to do that instead of needlessly paying more and not getting more
of a benefit for the expense. What most of us already know: the best gas is ethanol free.
(regardless of the octane rating) In the long run, ethanol free is worth the extra $$ IMO,
but not premium grade when regular will suffice.