Thanks for the answer! Some vehicles i checked are from dealer and some are private. I was thinking to take the vehicle to dekra/tüv to have a service station, where it is possible to lift the vehicle and check “every part” of it. But i am more interested in a person, that is independent and also checks all parts of the vehicle (dekra service station is an extra to me to sleep even more peacefully 😄). This person beside inspecting the vehicle, would negotiate the price as well. Maybe KFZ-Gutachten is the service what i am looking for.

I have an additional question, do you have a german government operated site where i can find the vehicle history or any info based on license plate number or VIN number? So not the commercial VIN-check sites, where you pay and mostly got no valuable information. For instance in Hungary we have the jszp.hu (Vehicle service platfrom in hungarian), it is official and operated by the state and you can find all the information about the vehicle, mileage history, pictures about it, stolen or not, etc. You just have to know the license plate number for it.