A decent balance would be facilitating an interrupt/rollback of the update at any time. If you need the car now, and it's updating, it should be trivial to hal

A decent balance would be facilitating an interrupt/rollback of the update at any time. If you need the car now, and it's updating, it should be trivial to halt the update and operate the car on its previous software version. Storage is cheap nowadays, there's no reason to not have versioned copies of every operational software version across the vehicle.