Started the trip getting around 18 litres per hundred which was the best we normally get but the next fuel stop it had jumped to 30 litres per hundred , did have a whistling noise which I found to be a loose bolt on the turbo to intake manifold but tightening it up never improved anything other than the noise disappeared .
Air filter new ,fuel filter new and I'm stuffed as to what it could be but might have to cut the trip short if I can only get 300 kilometres to a tank .
At Woomera now so going to drive at 90 Kay's an hour till the next fuel stop and see if it makes any difference .

Anyone have any idea of what could be going on ?