Firstly apologies for the awful "drawing" 
It drives me mad that the developer didn't wrap my garden around the side of the house, given that my front garden sticks out anyway and there is a wall there. There are windows in the side of my house and I am desperate for a bit more privacy!
As you can see, we have a large shared driveway. We all own a chunk of the driveway which we are responsible for, but must allow access over it at all times. "My" bit is within the black dotted area, so next to my house (plus the bit in front of my garage but that's irrelevant). I want my garden to be extended to the green dotted area. I can't see how this would be of any detriment to my neighbours, other than it being a bit unfair that I get a bigger garden. Is there any way I can pay them (if they agree, obviously) to allow me to extend my garden? I was thinking access for fire engines etc, but the wall sticks out anyway so it wouldn't restrict access any further. The driveway is already very wide and two cars could still easily pass. How would I go about this, if it's even possible?