My old passage GT got well over 600km from a tank but it was mostly constant driving back and forth from bunbury to mandurah at 110km!
Oh i forgot to mention that it had a stock RB20 "ET", manual and 65L tank. The A/C didn't work and the windows always stay up. All of which would help i suppose.
My R33R auto gets about 450km to 480km tank going easy, mostly on cold nights.
Got to thank boss for the work van and fuel card, only have fill up once a fortnight!