I think not, since I've shut down the engine a few times in a long downhill on an empty but curvy road and been able to steer. The steering and braking assists

I think not, since I've shut down the engine a few times in a long downhill on an empty but curvy road and been able to steer. The steering and braking assists (not sure what they're called in English) won't work though. Maybe if you turn the key all the way to off, putting out all the electronics etc. you might lock the steering.