No, they would be able to bundle their own entertainment system with their cars, but they would not be able to force anyone else who wants to use their engines in their cars to bundle the entertainment system as well, as a contractual precondition to be able to use those engines.

Of course the size of the company and the market dominance comes into play here. It's not a monopoly if people can go elsewhere to get their engines, it is if there is only one realistic choice of supplier (Android).

I don't love this ruling (and I probably disagree with it, but I haven't read the whole decision or the laws in question yet, and as an American, am not 100% clear on EU precedent so I'm somewhat withholding judgment), but yes, in most cases, anti-monopoly laws only apply when a company becomes large enough. In the US, it's actually explicit - monopolies can actually only exist if they are using their status to impact pricing/consumer choice, which necessitates size.

Exactly. That is the whole point of anti-monopoly laws.

> So it's only against the law once the company becomes big enough?

Yes, that's exactly what monopoly abuse laws are for.

Yes, this is how the law works. You surprised?

Yes? When you’re in a dominant position in a market you’re subjected to a different set of rules. This is to help keep even a captured market competitive.