I get a similar situation to this when queuing for the roundabout near my home. I can't go on the pavement (sidewalk) as I have the trailer on the back. I take the lane (well I have to really, with the trailer), and either scoot the bike with my feet, or wait until the gap ahead of me is long enough to justify pushing off. dh reminded me that just because a car crawls 6inches forward doesn't mean that I have to. Re the fumes - I just console myself with the fact that cyclists breathe in less exhaust fumes than everyone sat in the queue in their cars.