I've had a 2013 Model S until a few weeks ago and just picked up a 2015 CPO. Previously when I approached the 2013 from behind, the doors would not unlock but the car would allow me to open the rear trunk using the button under the liftgate Tesla logo. Now with the 2015 this no longer works. I was just in Tesla service and they mention that this is a little different on different model year cars and that my car is working as designed. They say the sensor is in a different position. Can anyone help either verify this is true or debunk this statement? My VIN is 78xxx.