Down here there was a murder case recently. The suspect always replied prompt on his messages, except for the 2 hours during that murder. His phone was supposedly at home with him being out.
There were many more juicy bits in that case, but this part is somewhat in the context of the discussion. The message seemed to be, plan better next time :)
Joke aside, your car probably has a mobile connection by now and even the dealer/manufacturer has access to the data which means authorities don't need more than to purchase it. So you might want to leave the car at home too. And the smartwatch.
This gives me a morbidly hilarious mental image of someone trying to dispose of a body using a bike trailer or cargo bike. Perhaps the rider might even feel a little self-satisfied about how environmentally friendly they're being by doing so.
I suspect the cameras on buses can used to track where you're taking the body. Maybe also where you tap in/out with the extra fare for the bulky cargo.