First drive with my VW T3

Yesterday after work I drove from Warsaw to Łódź. Via Sochaczew and Łowicz, about 145 km (90 miles). I bought fuel on a gas station at the road to Poznań. I was travelling fast, about 90-100 km/h (55-60 mph) because I was in a hurry and wanted to see how fast can my bus drive. It has broken speedometer, so I'm not sure what was the real speed. Today I drove the same way to Warsaw and bought fuel on the same gas station. 250 kilometers and 22 litres (155 miles, 5.8 gal), 8.67 l/100 km (27.1 MPG). A LOT! I'm not happy with that result.

Seems I have to drive slowly. And start fueling the camper with vegetable oil.