What is the reversing mirror trick?
Put the car into reverse, turn the mirror switch to passenger side and adjust it to point down to the kerb. From now on when you select reverse and the toggle is in the passenger side the mirror will dip to the same position every time, giving you a better view of how close you are to the kerb. When you select drive - the mirror goes back to its original position.
V handy if you've got big alloys you want to prolong!!!