Gas stations
The network of gas stations can be sparsely populated depending on the location. You should therefore always fill up before longer journeys as a precaution.
Fuel prices are slightly higher than in Germany. However, the fuel prices on the highways are no more expensive than in the cities (in some cases they were even cheaper).
When filling up, you often pay by credit card at the pump. If you have linked your credit card to an app, you shouldn't be surprised if you receive a push message about an overcharge. This is a kind of security charge. In the end, however, only the actual fuel price will be debited.