What actually happens is they get close to the house with a radio scanner and read the code the key is giving out, then retransmit that code near the car. Nothing to do with wifi in the car. More recently manufacturers have instigated a feature that the key goes to sleep and stops transmitting when it detects no movement for a period of time.
Sarcasm - tut tut 
I tested this with the misses T-Cross, full kessy, put the keys next to the door on a step, the car would happily open and close. Left them there, and 10 minutes later unable to unlock the door with the keys where they were resting but unmoved.
- but my view and opinion is that for every new tech that comes along their is an army of folk trying to infiltrate its weaknesses for criminal, "dark" and self-gain intentions, and the more we integrate this tech into our lives, and perhaps we have little choice on the matter, the more vulnerable we may become. Most may perhaps think that's foolish, and some say, stop reading certain papers, and that's OK, but my preference is to see tech as a tool to be used wisely, but at the same time, be wary of.
