Yup, there should be some way to choose manually. I have a quite dumb phone which I never use to connect the 'net, and I often enter fuelings after several hours or days, maybe hundreds of kms from where I live or work.
Though I don't know how it'll handle stations in Europe to begin with, this whole thing might be academic
For clarity, when I mentioned road map, that was a term used to describe our business plan, not an actual feature. That being said, we'll definitely design the system so you can manually select your gas station.
I live near a Williams Pipeline terminal and tank farm. On any given day one can see gasoline tank trucks from almost any local brand, including house brands, tanking up. I presume at least some of them also tank up with diesel fuel, since most tank trucks have more than one tank. This tells me pretty much every gas station in the area is using the exact same fuel, although it is said that the tank truck drivers put whatever additive package is called for into the tanks along with the bulk fuel. I have no idea where the ethanol is added for E-10.