People found the concept of computer control over an idle stabilization valve terrifying in the early 80's. Killer cars, everyone predicted. It never materialized. The lawsuits against Audi never went anywhere, and Audi even won some counter-suits.

Most cars have drive-by-wire throttles. Hundreds of millions of cars out there, and DBW throttle failures leading to crashes are unheard of.

You know what is an issue? Ford unable to make ignition switches that don't cause cars parked in house garages to catch fire. GM cheaping out on their own ignition switches, causing them to suddenly fail while driving....and thus shutting off the engine, ABS, and airbag systems, something that is known to have caused the deaths of half a dozen people and likely tens if not hundreds of other Cruze owners.

I've been reverse engineering a modern ABS control module. It has 2 cores, and they are separate CPU's with their own memory (although one cpu can access the RAM of the other CPU) and role. One reads/writes the CAN bus and does verification on that data, the other CPU is the one that monitors wheel speed sensors and determines when to control the solenoid valves. There is a cleanly defined area where data is copied from one CPU to the other.

While I agree with you in general about being careful about the pitfalls of multi-threading, the automotive industry is fairly competent at safety and correctness. They are probably the only few industry making good use of formal verification. In short, I am less worried about cars not working due to misunderstanding of C language than any other device like my PC or iPhone