@Lutz
I thought your dropdown was the Serial Numbers? (from your picture)
But, right, that is why I mentioned that you will need to use your Datasource as the Items property of the dropdown.
If you use Choices, then are you stating that the Model column is a Choices column or a Lookup column in your list? I am going to assume that it is a lookup since you see both Value and Id.
So, if it is a lookup and you want to show the referenced column of the looked up list, then you would choose Value.
If you could provide more details on your data list and the column types and what you expect to see in your app and in what kind of control, that would help get to a solution faster.