You will need to supply a few details about your Patrol
Any engine modifications?
How many km has it done?
Ute or wagon?
Any other accessories, such as roof racks bull bars etc.
How much weight does it normally carry?
What sort of driving; city, country, hill, flat etc.
Towing a trailer?
And that's just for starters
But most importantly what is the actual fuel consumption in litters per 100km (L/100km)
Without that consumption figure no one can tell if it's really using a lot of fuel or not maybe what you are experiencing is normal.