What's this opening at the side of the car about? It is at both sides of the vehicle. Depicted at the box there seems to be a yellow cap, which will fit to the color of the car itself. But I didn't find this (or something similiar) within the box. Interesting is also, that in contrast on the plan the schematic figure doesn't show the "yellow" cap either, like in real life there is this gray opening.
Has there been something missing within my box? What is this opening for?
Is this the fuel tank opening? If so, why are two of them? Maybe I should try in this case to find a cap for it; cf. also my discussion/thoughts about
fuel caps.)
Or is this for something completely different (maybe the truck base is used for another set too in which the openings have a specific purpose).