I don’t think the car brand comparison is a great one. While I get your point, the purpose of using different car brand names is not for confusion but actually to reduce confusion — to clarify which products are targeting a luxury market.
For a counter example, consider how Samsung sells premium and cheap smart phones. The cheap smart phones give Samsung a bad name which might be associated with the higher end offering in the eyes of a consumer.
It’s not fair to compare to Toyota to Lexus because a Lexus is targeting a different customer and making different trade-offs in their product, even though it’s the same company.
The recent Pi chips are heavily modified. They’re becoming less and less like their TV tuner roots. I wouldn’t exactly call it a failed product line either. I thought that IP went into numerous devices.