Don't go by the DTE on the dash ... mine has never read more than 530km on a full tank, but I almost always run over 600km (highway) with another 100km or so in the tank. There's about a 7.5L 'reserve' still in there by the time DTE is reading down around 20km left, according to my fill-ups. I've run it to where the gauge on the dash doesn't even register anymore and it still didn't take 60L.
From my Fuelly records, my emptiest tank was with 653.6km and it still only took 56.206L - the most I've managed to add in a fill over 8800km so far. The DTE on the dash is HYPER conservative.