ZD30 Fuel Consumption

Hi Folks,
I have a Patrol ZD30 auto with 10,000 k's on the clock that I've had since new. The best fuel consumption I've achieved was 14.2ltrs per 100k driving around the outer suburbs of Brisbane, (not in peak hour traffic), with some highway work. The worst was towing a 1000kg camper trailer where I used 16.5 ltrs per 100k.

We have just returned from a 2000k round trip towing the camper trailer (1000kg) where I averaged 15ltrs per 100k highway driving (cruising speed was usually 100kph). So far, the Nissan owners I have spoken too, reckon they are getting better towing economy than that, even when pulling 2.5 ton full height vans. My consumption when I'm not towing does not appear to change much. On the forum I see in the discussions, people claiming figures of 900-1000k from both tanks (not towing of course). These are figures I can only dream about.

My Nissan dealer reckons my figures are acceptable for a 3.0 lt patrol.
The ADR label on the vehicle indicated 10.9lts per 100k. The only way I could achieve this would be by getting a tow.

Are my figures comparable with fellow ZD30 owners? Is it worth getting a dynotune to see if there is a problem? or do I learn to live with the sucky fuel economy?

Any advice would be appreciated.

Thanks, JJ