Solved - NEH 5102: Borgward 1500 RS - 1958

[hermanoto]

The 4M 1.5 II got direct injection onto the 'old' engine.  In 1956 a new engine with direct injection was developped for the 4M 1.5 III.

[sichel]

Yes, now the case is settled. Here is your next point 

[Wendax]

I think it is the same car as this one: https://www.autopuzzles.com/forum/2017-47/neh-5102

[Carnut]

I think so too, so I'll merge them.

[sichel]

In my photo, the side vents behind the exaust are not easy to see. So I didn't realise that it was obviously the same vehicle. But instead we now have an illustration of this magnificent engine and know a little more about its development history. I am inserting a table for this purpose, their optical quality corresponds to the original.