What about comma? https://comma.ai/ Seems like our old friend geohot built exactly what you want.
Positive HN discussion: https://news.ycombinator.com/item?id=36927971
Positive HN discussion: https://news.ycombinator.com/item?id=36927971
I think the argument is that we won't see the same availability beyond level 3, since level 4 is the first step where a human is not required behind the wheel. This means you probably need subscription to have a remote human who can step in and take control in edge cases, at least until we develop AGI. Even then, I suspect the economics of running a full AGI from each vehicles will make a subscription mandatory.