It seems that the difference in consumption between smaller petrol/diesel 4x4s is more noticeable. eg Landcruiser diesel 13-15L/100km, petrol 14-17L/100km. Pajero diesel 10L/100km, petrol 15-17L/100km.
I had 2 petrol/gas Patrols (98 &99), most reliable and tough 4x4 I have owned. BUT they used gas at 26L/100km and petrol at 22L/100km. On a trip I would get 450-500km from 80L gas and 50L petrol towing the 850kg camper. LPG was cheap but filling up 85L every 300-330km was a pain in the arse and that was the reason I changed to a diesel.
Now I have an 04 diesel Pajero and I get ~700km from 80L. Cost the same as the Patrol on gas but without the worry of running out. Much more convenient with the missus and 3 kids, for us anyway. I also love the way the diesel delivers the power too, very flat torque curve in the auto, no matter what rpms/speed/load she just pulls as required. Not fast but solid.
New low capacity CRDs may be different, I have only driven a 2010 manual D22 Navara, that had nothing under 1800rpm but when it hit 2000rpm it was a different car!
I still reckon it crazy not having a diesel Patrol/Pathfinder in Australia. Would like to see a sales comparison in a years time...