My mum did her driving test in my dad's old Rapier, which was kitted out as a rally car - daylighters on the bonnet, forest tyres and full harness seatbelts and it was upgraded to disc brakes and had a blueprinted engine. The problem was, the passenger seatbelt was loose and would flip forward... Not a problem if you were wearing the full harness seat belt.
The instructor got in and my mother asked him to put on his belt, he refused "I've been driving for years blah blah blah..."
They went out and he told her to stop quickly when he tapped his clipboard on the dashboard. My mum's reflexes were quick and she was nervous, as he raised the clipboard, she slammed on the brakes - and stopped without skidding (although the rear wheels probably left the ground

The instructors head smashed against the windscreen before his clipboard reached the dashboard! As he was knocked unconcious, split his head open and had to be taken to hospital by ambulance, my mum failed!

BTW, in Germany, you cannot drive a non-driving school vehicle on the public highway until you have a full driving licence, so no private lessons / hours. You can drive to a private testing ground and pay a few Euros for a couple of hours driving around simulated streets with other novices.