Petrol stations in Germany make almost no money on petrol. I think it was something along the lines of 2-3 cents/liter. I am quite sure that they will be happy to have customers stay in their shop for longer.
That's still quite some decent margin. It takes about 5 minutes for me to fill my 40L tank, which would be about 1€. Everything is automated, there is absolutely no human involved, and it works 24/24.
There are extreme construction costs for petrol stations. It's highly regulated due to the fire risk and other issues. You can't even lead surface water into the gutter without prior filtering.
It's spending about 4 to 5 EUR for about 350 to 400ml, not tasting any good in any variation i've tried (because captive audience at the moment) and afterwards angrily wondered why i did it AGAIN?
