Passat Blue Motion – average km with one tank filling

Hello Community, Since I’m going to have to start planning a new car within the next few months, I’m going to move to the border with Switzerland (not yet known where exactly) and then commute every day (5 times a week) from Zurich and back. Of course I have about a distance of 75-90 km (per way) and about 1 hour drive (per way). That means I come to about 900 km a week (only working way). The BlueMotion will manage that easily, I don’t doubt it, but now the question, if it is only 75km per way and I will drive the second car of the woman on the WE, then I would get to just 750km. Is it possible that I could only fill up every 2 weeks without having to exert myself extremely hard and thus I could get more than 1500km with a tank filling? Or could I even manage 1800km with a tank filling (that would be really fuel-saving king driving then) ? Who of you has the latest Passat (Model 2013) and what do you get from me a tank filling? Thank you very much. 😉