Replicate Tesla (PKE)Passive Keyless Car Entry using Arduino and bluetooth

I have a tesla and it allows me to unlock the car with my phone. I don't even have to take out the phone or run the tesla app. I simply walk up to the car and pull the handle. Somehow the car detects my phone bluetooth and unlocks. The question is how to do this with Arduino? all the bluetooth chips for arduino require i run thier custom app on the phone to connect to the bluetooth chip. I want arduino to auto scan for my phone. I don't even know where to start. Is it with the BLE 4.0 or the classic bluetooth? Any pointers? I am sure someone must have done this before.

If the car already opens when you approach it, why would you also want to unlock the car with an Arduino ?

I don't know about xweili123, but I'm working on a robotic arm to automatically plug my car in when i park, and unplug when done charging. The goal is to help extend autonomous operation past a single charge cycle, and reduce probability of accidentally forgetting to charge on a day where I really needed the range the next day.

However, I think OP is actually referring to having the arduino recognize the phone when he approaches the arduino. Whereas I want the car to recognize the arduino when the car is in the garage (you can only open the charge port if unlocked, usually).