ForeignKey or ManyToMany field search in Django Admin

Assuming you are on the VehicleInfo admin page, in your admin.py, try adding :

search_fields = ['vehicle_name' , 'vehicle_type__vehicle_type' , 'manufacturer__manufaturer' ]

Staring with the Vehicle model, vehicle_name searches on that field.

Now manufacturer__manufacturer will search on the manufacturer. The double underscore indicates that it is not a field on the same object, but a foreign key to look up, so the first manufacturer points to the manufacturer model. The second manufacturer tells it to look up the manufacturer field on that model.