$0, as far as I know. For example, Ford has HackerOne programs but only pays bounties for an extremely small set of their applications. Other companies had no program at all, like Ferrari, and we had to message them on LinkedIn.
(I worked on some parts of this research.)
Is there a way to leverage any of this for a jailbreak?
It would be fun to buy a Prius Prime and play Quake on it with steering and horn as controls.