Diesel Additives: Improve Fuel Efficiency & Performance

Hello,

I heard from a friend that there are additives for diesel engines that are added to the diesel fuel.
Apparently, the fuel injectors and other components need to be cleaned.

Is this just another useless invention from Volkswagen, or does it actually have any value?
Does anyone know the exact name of this stuff?

Deleted upon request.

Try using the search function. There are numerous reports about cleaning injectors using additives.

Best regards, D.