my xm got way more than 1000kms from a tank. an average of about 7L/100kms and an 80litre tank
On trips down to Melbourne in my greatly missed Xm, I also routinely got more than 1,000km from tank. After the intercity drive I had enough fuel to drive around the suburbs for about 200km. Of course that was with the PRV V6.
The most fuel I managed to get into the tank was 88 litres. That was after it wouldn't start on a slope after the flow fuel light illuminated.