Am I missing something? Should there be an icon that I can enable? Having searched the board I wonder if I am just as bad at finding information

I am aware that this could be avoided if I simply "picked up" the tank whenever I leave it. BUT as I tend to tow around loads and loads of things I think might come in handy, there isn't enough space for the fuel (of which I also have loads and loads inside the vehicle ... I HATE driving with less than half a tank contents).