You know, in terms of gameplay the Enduros are the area of biggest disappointment for me (after AI). I've said this many times before, but pick up a copy of Le Mans 24hrs to see how Enduros should be done. Big grids with different classes, weather (effecting grip), weather forecasts, pit action, changing settings in the pits, atomsphere eg big cheering crowds as you go past the main stands) and day/dusk/night/dawn either at real time or with a 3x time (clock only) setting turning a 24hr into an 8hr race.
Sure you can't do all that with the GT4 on the PS2 but day/night and pit saves should have been done. But maybe I'm being ignorant and 24hr racing in Japan is done when the sun doesn't set.
PD owe it to their customers to check out that game before giving us GT5.
Steven