Currently the Model X and Model S does not support using your phone as a key (as passive entry). Sometimes it's nice to not have to carry around a key fob.
The idea would be to bring this same feature that's in the Model 3 to the Model S/X.
Update: With the redesigned Model S and the upcoming 2021 Model X, Tesla has now implemented this feature. It appears that there may have been some technical reasons why they couldn't add it to previous models, but all future Tesla models will now support using a phone as a key.
Yeah, we will add that as a feature
— Elon Musk (@elonmusk) May 10, 2018
