I agree there are times when you require the space more than the cars. Recently when there has been a lot of snow and ice, the only non-slick spots are where the car tires go. This can be problematic. In this case, I will often stop and pull off of the road to allow a few cars to pass and then follow the pack of cars.
One point should be made: one should not ride in the gutter just to allow for space for cars. The gutter is a very dangerous place to be. However, most roads there is plenty of space to ride beyond the gutter plus enough room for cars to safely pass by. I consider this a requirement for a road that I will regularly take on my way to work. That is the beauty of the Google Maps bicycle route function; it gives you a lot of options to try out. If there is a road on one route you don't like, pick another route.
My main point in this post is that because you are are enjoying so many benefits from bicycle riding, you should be willing to give others a break and allow them to go first if they seem stressed out about the situation.
