The VW, obviously. With most parts shared across 13 models and all models static for at least a year and usually longer. Plus VW has a good history of parts availability.

Tesla on the other hand is famous for both making minor changes to their vehicles pretty much continuously and a bad history of parts availability.

I have hosted the models (mostly regression and random forest) WV use to predict missing part availability at their dealership in 2018-2020 (considering sales in the area, average fabrication/delivery time, likeliness of the part having to be replaced, probably others).

I guarantee you that even if I don't like their car, their dealership will very likely have the part you need around the time you need it. It's not the only car-adjacent company that does something like this (Valeo for sure does it too, i worked with them also), but I'm pretty sure it's the only one who has an internal data scientist team working on it.

Is this a trick question? I know the Tesla software locks as much as possible to prevent third party repairs.

... What makes you think a VW ID.4 is obscure? I think it's usually the best-selling electric car in Europe. You see way more of those with recent (last few years) registrations in Dublin than Teslas.