Maybe there could be a future option to allow proximity to be user defined based say on signal strength?
Could easily be that it already does this. Some of us just have stronger signals than others.
Seems likely that Bluetooth would adjust its transmit power to a minimum required to achieve the communications data rate it requires at the time. Probably controlled by the receiving device (the car), which knows the signal to noise of the received signal. So maybe Tesla is asking for a really low power from the phone to see if it's close enough. Maybe the phone says it's at its lowest power. But maybe the phone's lowest power is higher/lower than average. The Tesla might think the phone was nearer/farther away than it actually is.
One workaround would be to measure the time for a round trip signal and acknowledgement. But what if the phone delays a little more or less than average when sending the acknowledgement? The car thinks it is farther/closer than it actually is. This is a simple problem only if Bluetooth has a standard feature to do this.
My Android Nokia 6.1 needs to be out of my (front) pocket, and sometimes turned on, or our Model 3 won't unlock or start. After I'm sitting in the car and have pressed the brake pedal to start the car I can then put my phone away. For unlocking, some of the delay might be just the phone powering up after powering down to save battery. But if I get the car unlocked it still won't start if I've put the phone back in my pocket before sitting down. No way my phone will work from 7m away. Although it will say "connected" throughout my house, so the signal is there but doesn't trigger whatever Tesla is looking for to unlock the car. My X's key fob is a different story.
