I only started commuting a few months ago, but ever since, I've noticed how much car pillars etc. obscure your vision. Was completely unaware of this before I started riding on the roads rather than trails.
Also, I've become a lot more aware of how cyclists behave and their space requirements etc. I reckon the TAC motorcycle advertisment where the motorcyclist and car driver swap places is great, and I think one should be done swapping a cyclist and a motorist. Letting drivers know about 'clipping in', stopping, turning, dodgy road surfaces etc. would hopefully make cycling a lot safer.