Well, anything unpopular that doesn’t use any software (even low-level software) that is also commonly used in popular environments. For example, game consoles, embedded devices or car entertainment systems often use outdated versions of popular browser engines. So to hack these, you don’t need to be a highly skilled hacker, you just need to be able to try some older vulnerabilities.

And there are enough malicious websites that will just automatically check for these vulnerabilities. And then it’s enough to accidentally open one of these malicious websites and even though nobody wrote the hack specifically for your car, you might catch some malware regardless.