I completely disagree with you about the Microsoft thing. Forcing individual users to have updates installed, informing them that it's going to happen, is absolutely in the users' best interests overall. "Not installing updates" is the absolute #1 cause of malware spread. Up-to-date Windows 10 machines were 100% immune to the WannaCry worm (the recent one that crippled corporations and hospitals around the world) a month before the thing was even released.
Cars, on the other hand, don't have anywhere NEAR the attack surface (the metaphorical ways and amounts of vulnerabilities that can allow an attack to proceed). Access to the internal programming is strictly limited: it's on a physical access only model, by people that have made significant investment to be able to do so, and (generally) happens only with software directly from the manufacturer, with enough testing that the manufacturer willing to pay for problems caused. Cars don't interconnect with other cars; they don't accept updates from other cars, and they don't even pass information about other cars along.