Oddly, in all my years of working alongside police (in a fairly large California county), I've never heard of anything more than analysis of pings and google data. In the case that was reported in detail in To Live and Die in LA, no attempt was made to tell where the victim's phone was aside from where it last pinged (whether it was in a car, or at hip height, or whatever).
I'm wondering if all police departments do this kind of forensic work. It would surprise me very much if San Bernardino (less resource rich than where I work) had done this.
Further, if a person put the phone at a height consistent with being inside a truck, how then would anyone know? The person could say they forgot their phone, returned later quickly to get it. Not that I think anyone asked anything so specific on a lie detector test...but if they did, it might cause an irregular result. OTOH, things slip the minds of honest people all the time.