i have a wagon too and drove from sydney to jindabyne snowy mountain on a full tank of 95 ron it was just over 500km, then back to cooma another 100 km with just on the empty mark, i think used more fuel going down than i did going back home, i can remember only getting 40 into the tank though, and also using a higher ron fuel to go abit more in distance, but there are different varibles with getting economy, weight of car , driving style, fuel , good music lol