pure road tyres make a huge difference , my td5 disco has 18" pure rd tyres or 16" full mud terrains , the difference is about 90-100 miles on a tank
the 110 runs fully loaded with heavy winches front and back on 265 muds the fuel on that is horrendous but goes with the right foot treatment it gets as it has a disco transfer box which is a bit much for it with the big tyres
roof rack makes a big difference too