Don't know the specifics of the Audi Q7 of the OP, but my Mercedes A 180 CDI 2012 model (Diesel engine) averages 53 mpg (4.4 l/100Km) for my conmute trip (35 KM total, including ~8 KM of mountain road, with a 300m elevation change). Given that my A180 has a 50 liter (13.21 US gallons) fuel tank according to the manufacturer, that means I could make up to ~1,100 Km with a single tank. In practice I refuel before that, but routinely make ~900 Km between refuels.

Audi A6 diesel (yes very much a dirty VW/Audi diesel-gate diesel, although supposedly "fixed" now). It does 40-45 mpg US (5.5-6L/100km) and the tank is just bottomless (17 gallons/65L or something?)

> I envy you.

Still envy me when I say a full tank is $100? :)

:) I'd spend about $130 or more for the same 1000km.