If you're still wondering, watch this:
https://www.youtube.com/watch?v=FPPkPAbzwbU
I can't believe that the head of the Canadian petroleum industry doesn't understand what premium gas is for.
If you really want to spend more money for better gas, buy Top Tier gasoline
http://www.toptiergas.com/.
Not only can our old cars with stock engines run as well on the lowest octane available as on any higher octane, the higher you drive in elevation, the even lower octane you can burn. That goes for new cars too. If you're driving a new car that requires 89 octane at sea level, it will do just as well on 87 octane at 5,000 feet elevation.
Just remember, higher octane is only for higher compression engines to prevent premature detonation. It has no other benefits. It is not more efficient, not more powerful, not cleaner, and, in fact, is worse for the environment when run in a lower compression engine like ours.