They can keep driving until they switch the car off. Some systems switch off gradually after a longer way.
There are two main reasons for that. Over use that if your key dies, you do not want your car to stop immediately, this is not safe. The second one is carjacking: you want the thieves to have a useless car further from you (that one is I belive just a collateral or a secon thought)
Usually it’s just to gain entry without setting off the alarm. Then a keyfob is made using OBD. Either in the driveway or 100m away if the vehicle so permits without an existing key.
There are two main reasons for that. Over use that if your key dies, you do not want your car to stop immediately, this is not safe. The second one is carjacking: you want the thieves to have a useless car further from you (that one is I belive just a collateral or a secon thought)