I was out for a drive last night (no I was not topping up my tank)
As I drove and was passing cyclists I had a good hard think.
Is there an easy way to tell how much room I have in the lane to know how far out I can be?
Then the thought struck me - the white line in the road is where I want to be keeping my driver side wing mirror within. If I know where my mirror is in relation to the white lines I will know the line to take to leave as much space at all times so I lined the car up on a parking space white line (nice and long, no moving traffic. Noted where the line was along the bottom of the windscreen and looked out the window, repositioned car until I found the sweet spot (somewhere halfway between the edge of the wiper and the corner of the screen)
Now this will work for any driver in any car (obviously taking into account driver/seat height/position and different srivers in the same car) and could be easily marked on the screen with a tiny bit of tape (maybe one colour for each driver's setup)
Once drivers know this position on the road they can leave as much space as possible for cyclists when passing them or being passed when cyclist filtering