they put so much crap in fuel these days that it goes off in no time so you gotta get it fresh. The premium fuels come from the branded refineries, so in SYD that means it's shipped from Perth or briso. The regular unleaded is bought from whatever refinery is in town. Up here in briso we have a BP/Ampol refinery so we get the true "ultimate" fresh out of the tower but in SYD you don't have a BP refinery and the BP tankers are seen to come out of the Shell refinery at Sandown -

The consensus is Caltex 98 is the performance fuel to use in SYD