I was in a car park today and I actually drove about 20 yards without being buckled up ... and my car went MENTAL at me!!! Flashing seat-belt sign on the dashboard, and a highly annoying continuous warning siren. If that doesn't make you belt up, I don't know what will 
Always wear one, but only shoulder strap part.
I put the other bit behind me due to a medical condition.
It's that or not wearing one at all!
You mean the lap belt behind you? I'd imagine that's very dangerous - in a crash your lower body is going to slide forward and drag you down in the seat and the chest belt will probably end up strangling you.
It's that or don't drive I guess as I was told I would not be insured to drive without one on.
Why don't taxi drivers wear them?