Oil and power plant nearby

Isn't it too bold to just ring the neighbors' doorbell?

No, if it's at reasonable hours and if you politely say hello. If the native then reacts strangely, that speaks against the property as well ;-).

Saturday afternoon in nice weather, 50% are sitting outside.

The highway might bother me more, if applicable. How far away are you really?

Thanks - who can help me more specifically with that?

How is anyone supposed to help you more specifically if you don’t answer the questions about it?

Since it was visible in the picture, I'll just write it here: Lessingstraße in Hassel I estimate about 600m as the crow flies to the motorway

Since it was visible in the picture, I'll just write it here: Lessingstraße in Hassel I estimate about 600m as the crow flies to the highway

The highway is located west of the property – you will hear it.

Make up your own mind about the surroundings. Buying a property is subjective: whether you like something is often decided by your gut feeling and your previous lifestyle habits. And: a house has a doorbell to ring; even in the age of forums, you are allowed to address strangers ;)

Since it was visible in the picture, I'll just write it here:

I estimate about 600m as the crow flies to the highway

Which picture?
But whatever - as soon as there is a west wind, you will probably experience odor nuisance.
The highway nearby - well, a matter of getting used to.
My sister's house is near Leipzig airport, which is also the European hub of the German Post.
My sister and my parents regularly get annoyed by it (airport expansion and the start of DHL night flights happened after the house was built). The noise bothers us less when we visit (except when a low-flying plane comes).

You should really plan a whole weekday and a weekend day and go there (possibly checking the wind direction beforehand using a weather app). Spend the day on site (possibly in a café nearby) and talk to neighbors.