Guard a BMW ? -- You cannot be serious
I did sit in the cab of my van once watching a woman with a Vauxhall trying to find reverse - After 20 min I did get out and asked if she wanted help. You have to pull that little knob on gear stick up. She was so grateful - This was well before mobile phone days so she couldn't ring for help.
Now you would be accused of "mansplaining". So best to just leave them to it for the rest of the day