Solved: Wendax 345 - Umba 4/14 PS

[Wendax]

No, the marque is not mentioned at wikipedia.

[grobmotorix]

I do not know if it is mentioned in Wikipedia, but my final guess for this is "Sauer".

[Wendax]

It is not a Sauer, sorry.

[Wendax]

So the question remains:

[pnegyesi]

Is your contemporary source a magazine focused primarily on cars?

[Wendax]

No

[pnegyesi]

can you help me just a tiny bit and tell me something about your contemporary source? Is it a sporting magazine?

[Wendax]

Its focus was on engineering.

[pnegyesi]

It's not in the VDI zeitschrift. General engineering?

[Allemano]

So, this is still the only source for this car? Amazing!

[Wendax]

Yes. There are a few very ephemeral mentions of the company out there, that don't go beyond its pure existence. The car itself is not mentioned on the web or in any book I know.

[pnegyesi]

"It's not in the VDI zeitschrift. General engineering?"

[Wendax]

It is not from the VDI Zeitschrift.

The publication was a weekly one about engineering.

[Allemano]

Regional magazine or published nationwide?

[Wendax]

regional

[Allemano]

I guess from the Hanseatic region

[Wendax]

Yes

[pnegyesi]

was it published in Hamburg?

[Wendax]

Yes

[pnegyesi]

hmm, I am a bit stumped. The title doesn't have the following words: ingeniure, technik, verkehr, industrie, metal, motoren. I don't have any idea of its title

[Wendax]

The German language can be versatile. May be not as much as Hungarian, but enough to keep you entertained. 
A derivative of one word in your list is part of the title.

[pnegyesi]

I tried technisches but no. Does it have anything to do with industrie?

[Wendax]

Technische is part of the publication's title. 

[pnegyesi]

You mean, Hamburger technische Rundschau?

[Wendax]

Yes!