I'm not super familiar with cars either, but for people that are, things like the fuel door and cap are unique between different makes and models. If you stare at cars enough, you just kinda begin to know these things
I was more referring to the efficiency side. In that a PSU is most efficient when between a certain wattage of power draw. Similarly, using a fuel formulated for high compression will be less efficient than one for low compression in an engine that is low compression.
Depends on the compression of the engine. I've got a 40 year old 125cc scooter that should arguably take premium, because it was rated 10:1 when it was new.
My car has the same compression ratio and asks for 87 AKI, which I believe is 91 RON. I have to give it 95 though because that's the lowest they sell here.
Funnily enough, car's only 10 years old. I'm surprised they didn't mandate something higher than... 87.