Also, if VW can figure out when their cars are out for test, I can't convince myself that google couldn't do a damn good job of hiding the network traffic, if they wanted to.
Like most in this thread, I am not _actively_ paranoid about this, but a constant low-grade paranoid.
Not if you don't use Android.
Yes if you use Android, and in particular yes if you've given an app camera access.
Proof: my phone (unrooted, OEM Android) can shoot photos whenever I want it to, even if it stays locked, without anyone noticing. It's a trivial Tasker job I set up myself (think e.g. shooting rear-camera selfies using your smartwatch), but it nicely demonstrates that any app with camera privileges could do that too.
I said if you _dont_ use android
Allow me to put on my tinfoil hat for just a moment and remind you that, should Google want to, they could just turn on your microphone and camera without letting you know. Would they? Probably not, but they certainly could, and unless you're in the habit of regularly checking your network traffic, you wouldn't know.