Friends like that who help you reverse, better be without.
Everyone has found themselves at least once in this situation in their driving life, where you have to reverse against a wall in a limited space. With or without radar and reversing camera, it is impossible to judge precisely the space that remains between the rear bumper of your car and the wall (or the obstacle).
The ideal solution is then to ask a friend to help you with the maneuver, watching with his own eyes the proximity between the vehicle and the obstacle. As in the video below, where a driver is assisted by reversing behind the wheel of his gray Golf.
Except that the friend in question shows a particularly generous optimism. So the easiest thing for him is to wait for the car to hit the wall so that it stops on its own. A friend who really wants you good, sure.