[moonbug]

the cars are transmitting? are you quite sure?

[LeonM]

For keyless entry, cars are always transmitting. They look for a response of a key. In case of my car, if a keys comes close enough, it lights up the doors and doorhandles.

[kevin_thibedeau]

Unless you want to recharge your fob every week it has to stay passive as much as possible. The car has a bigger battery.

[harg]

Some older fobs do recharge when in the car’s ignition. My old bmw did this and it was recommended to swap the keys from time to time to make sure they didn’t run out off battery. I guess this can’t be the case with the “keyless” keys though

[bondarchuk]

Could be a challenge-response scheme where all cars are sending their challenge at the same time, after the initial signal from the keyfob.