&gt;design decisions like this cannot be secreted into the final product.<p>I&#x27;m not entirely convinced. You compare it to the Linux kernel. I&#x27;d say a better comparison is router firmware upgrades.<p>If a manufacturing plant gets sent a new image with a note attached saying &quot;HQ says use this one&quot; then they&#x27;re definitely going to load it onto the cars.<p>Clearly someone cooked the image somewhere &amp; there is likely to be version control in place but I doubt the whole thing is as transparent code-wise as you suggest.