Originally Posted by martin mustang
if you check the manual, the option to start your car when the battery is down or near gone, i.e. no longer opening the doors, is to press it against the key sign in the steering colum, old place for keys, this way you be able to start the car, and get to a place with a battery replacement. nice feature, never the less I have a backup in my car just in case.
The key battery is not involved in starting the car. That's why the car still starts when the key battery is dead. But the battery helps you get in your car, so keeping a spare battery in the car is problematic.