Agree with everything you said as possibilities. There are clear proofs of concept that an accident can be caused by a compromised electronics, and multiple ways to do it. We can come up with endless possibilities, but I was trying to establish likely vs unlikely.
In his particular case, an attacker would require Hastings to be traveling at a high rate of speed to have a high probability of a fatal injury. Highland Ave is a 35 mph surface street. So the attacker would either need to speed the car up, or have him already traveling at a high rate of speed. If it's the former, Hastings could have just used the brakes. If it's the latter, there are lots of reasons why he could crash on a two-lane city street lined with trees and parked cars at 4 am. As you point out, it's possible a sophisticated attack could have also provided all kinds of distractions to prevent him from braking effectively.
I think the most likely explanation was that he was speeding and lost control, but feel free to disagree.
I was simply correcting your authoritative statement: However, steering and brakes are mechanical systems in Hastings' 2013 Mercedes C250 (like almost every other car)
You are dismissing it as unlikely, because you keep assuming that some subsystems would work as designed or intended.
I'm not comfortable discussing details on this point, but "just use the brakes" might not have been an option had the malicious payload been properly designed. I have maybe a basic to mid level of experience reverse engineering automotive firmware, and it would not be hard for me to pull off. God only knows what a state actor could come up with.
To get at actual firmware, you'll want to identify the ROM chips and wire up an appropriate reader. You might be able to get by with a bus pirate. Once you have the actual firmware, you should be able to identify the processor (get ready to learn old obscure Motorola instruction sets) and you're off to the races. If you luck out with an x86 or ARM processor I highly recommend the Hex Rays Decompiler.
I was working as a generalist on the team, so the HN expert collective may be able to give you better pointers on specific items.
In his particular case, an attacker would require Hastings to be traveling at a high rate of speed to have a high probability of a fatal injury. Highland Ave is a 35 mph surface street. So the attacker would either need to speed the car up, or have him already traveling at a high rate of speed. If it's the former, Hastings could have just used the brakes. If it's the latter, there are lots of reasons why he could crash on a two-lane city street lined with trees and parked cars at 4 am. As you point out, it's possible a sophisticated attack could have also provided all kinds of distractions to prevent him from braking effectively.
I think the most likely explanation was that he was speeding and lost control, but feel free to disagree.