Hi,
Apologies for the late response and this long reply. I asked a few dealers before my purchase about roof bars and had varied responses.
I did my some research asking dealers, chatting to other owners and also looked on the VW ID3 forums to see what other users had done so far. The Cupra Born was built off the same VW ID3 chassis I was told and so I was told allot of the same parts can be used on both cars.
My own dealer confirmed roof bars should not be installed, when I asked why his answer basically said due to how it affects the range of the car and not an actual issue with having them installed on the car.
I have watched a few videos of ID3 owners using roof bars and one guy with a Born using roof bars which seemed fine. They do not seem to have issues other than it affecting the range of the car as suggested and it would make sense to me.
I plan to use roof bars & roof box for our camping trips which we do roughly 3 times a year and I will be able to provide feedback then. Unfortunately this feedback will only be in 2023 as it is already too cold for my family to go camping this year. If I do test it beforehand I will let you know. I do not plan to drive super fast and do not plan to load the roof box with heavy items so I do not see any issues having a roof bar & box on my car. I understand it will affect the range and am happy to accept the consequences.
Here is a company which offers roof bars and I have seen a few ID3 owners with these installed.
Roof Bars from DriveDen