I've got one of those. I also have a green one with a cabin.
View attachment 330703
So, seeing Dutchelm’s car, i think its safe to assume these were factory.
I have the 45120 also, and, it has different spouts, on both the side and end, so, its unlikely a switcheroo (tech term)
Fwiw, BP Olex was the German version of BP filling stations, around for a short period, i recall about 1915-1930 ish.
So, the next question is……
Compound…..
Did this lgb 4040 version ever exist in a real life version?
And, if something similar did exist, what was the era?
The car materials warning symbols look modern, but that doesn’t mean the car design is necessarily the same.