I read it all, THIS was of most interest to me:

The use of fuel of too low octane can actually result in both a loss of fuel
economy and power, as the management system may have to move the engine
settings to a less efficient part of the performance map. The system retards
the ignition timing until only trace knock is detected, as engine damage
from knock is of more consequence than power and fuel economy.
This tells us that engine damage is not a big concern, as the management system will compensate for cheap gas. But it also tells us that we may not save anything after all, by buying cheap gas.

I'll do my best to save a buck on oil filters (WHEN I can find fleece filters in a local store) and on oil (by buying 0W40 at WalMart).

Other than that, I'll stick with premium gas.