This is the sort of thing that makes me realise how *complicated* an economic system is, and how "which choice has more freedom" isn't always obvious. Like, in principle, they could do this with anything. "Buy our car! But you can only buy X brand of coffee for the next five years." That's ridiculous, but it's not immediately obvious that it's wrong. But it is, because companies *can* always leverage one position into advantages in other positions. And if it's a small enough part of buying a car, ALL car sellers will do that, because being the "ethical car seller" isn't profitable enough and people will just put up with it. And "use our parts to maintain a warranty" sounds superficially plausible, but our instinct that it's a bit of a scam are right.