Am I misunderstanding something here? You want a car driver to pull into the outer lane so that you can undertake him between the cycle and car? I'm a biker and that sounds suicidal to me. The drivers next move would be to move back into the inner lane, right into you.

I've got no problem with your complaint about them half-changing and blocking both lanes, it's the concept of nipping between them, knowing full-well their next move will be back in.