Any ideas:
App Inventor does not work with Services, if you want to check if your mobile is connected to the car, you will have to open an application.
You can check if it is connected to the car by typing the car's Bluetooth Mac.
Here you have some information about advertisement with BLE:
The ESP32 can work with classic Bluetooth and with BLE, I have not tested if it can work with both at the same time.
Another idea would be to use Radio Frequency devices to get more range and open from further away.