With peoples' lives at risk and with cars representing huge investments for many people, it's probably about time to get regulation that requires the software systems that are interacting with vehicles to be open to experts at large.
The same goes for things like in-home security software.
The competition should not be in the critical software. That much needs to be standard. The competition should be around fluff, construction quality, body design, brand, perks, horsepower, etc.
How is this kind of thing handled in the medical and aviation industries? How about NASA? Life-critical and safety-critical software isn't something you should hire the lowest bidder to create, nor is it something that should be hidden away in the belief that "obscurity is (the best, and the only) security."