sounding like a broken record here again..
modern cars don't PING, or KNOCK! they have a knock sensor which retards the engine perf if the engine happens to run too hot for the fuel you are using. (higher octane rating basically means, higher heat tolerance before the carbon chain breaks.) if an engine normally runs hot, (designed that way to extract as much perf as possible) the fuel may prematurly combust before going into the firing chamber if the octane rating is too low. causing the knocking sound. knock sensor detects this, and makes sure the engine runs at a lower temp, (at less than peak performance) so there is no premature burning.
the drop in perf thanks to the knock sensor may not be too noticible, but as i've been asking for a while now, why would you spend extra money for higher perf (namely the 3.0 i6, or the 4.5 v-8) then be a miser about gas prices to lose performance? that to me is the dumbest thing, but most people cite couple bucks saved at the pump and lack of the knocking sound to justify such dumb decision.
btw, as unscientific as it maybe i agree w/ Todd (northyork) about super getting better gas milage. (this isn't a point of argument, just my observation from dring different cars and filling them up w/ different gas.)