I wouldn't dump millions into a custom GPS solution for that 1 time out of 1 million someone drives a car without a smartphone. Especially when that GPS system is guaranteed to be worse than Google maps and not as well supported.
If someone else drives your car they can connect their phone. Which is an improvement, because now they have THEIR music and navigation. See, it comes with personalization out of the box and automatically!
I use my car's GPS nav over my phone's because I don't notice being appreciably worse for navigating, but I do notice the ads on Google Maps being appreciably worse than the lack of ads on my car's nav system.
Also doing nav on my phone thrashes my phone battery.
We don't need 1 million different applications that we have to try to integrate together. Just let me connect my messages, my GPS, my music player, even my calendar. Personally, I could give a rat's ass how fancy Tesla's interface is or GM's. It will always, always be second best to what's available on modern smartphones.
