My 308 sits @3200 rpm at 110kph that's with 4 speed and a 3.36 diff. I have toyed with changing the diff and maybe go to a T5.
But now I'm just used to it, not bad I get about 300km highway driving out of the gas tank its 80 litres.
I don't do the kM you do. Its hard to compare this to modern cars economy but as I was told when my Sandman was new, fuel cost about 25 cents a litre.