A bit off topic, but this photo fascinates me.
I would never guess the car as the time period is way before my area of interest, 1935-1945.
However, I have once again become interested in automotive history in former colonial countries of that time period after joining this Forum and I wonder, Gerd, if your original source gives the country that this painting depicts.
It looks like a very upper class gentleman with the whip is "encouraging" a working class type as well as the oxen and horses to get the coach over the grade. As well, at least one passenger is seen to be pushing the coach and a lady and gentleman companion are trailing the whole mess.
The automobile driver seems to be raising his hand in triumph as he passes the coach, I assume this is the point of the advertisement, and the car looks to be sort of a "tourist" conveyance as well.
Finally, in the foreground is what appears to be a man in perhaps a European uniform and what appears to be a "local tribesman" with a rifle who may be providing protection to at least the coach, sort of like in the US Wild West.
Back to the painting and the question, is this to represent somewhere in French West Africa???