My Opel Omega B 2.0 DTI has a 70-liter-tank. I can reach -with carefully driving- up to 1100 km. The consumption is between 6.2 and 7.3 liters Diesel per 100 km.

My 1973 VW K 70 has a 52-liter-tank. It's consumption is around 11 liters per 100 km (98 octane "Super plus")

The prices were exploded in the last weeks. A liter of Diesel costs around 1,30 to 1,35 Euro, 98-octane-fuel up to 1,50 Euro.