Mirrors

Forgive a newbie question please.

 I've just got my first caravan. I have mirror extenders as advised, but I find I can see down the outside of the 'van with my car mirrors plus about a metre. The mirror extensions show largely fresh air, unless I move them inwards, then I can see the same as my car mirrors???? I tried to make sense of the regulations, as I thought I'd read that cars after a certain year didn't require extenders?