Everyone is different - coming from motorbikes I spent ages being told off for turning my head to check behind me and not trusting the mirrors (if any of you ride, then you will know just how useless motorbike mirrors are, particularly when they are vibrating and inherently showing the inside of your elbows). I also found I would go for gaps that were, ahem,'tight' or 'small' or 'close' - recallibrating me head to be in something much bigger and slower took a while. Reversing though was OK, there weren't any habits to break!
Dave (Enquiries, Wrexham Glyndwr University)