Well I did a quick search on Google and came up with this article.
Nissan Recalls Half a Million Models - U.S. News Rankings and Reviews
"A separate recall concerns the 2005-2008 Nissan Armada, Titan and Infiniti QX56, as well as Nissan Frontiers, Pathfinders and Xterras produced between January and March 2006 or October 2007 and January 2008. Vehicles at higher mileage levels may have faulty gas gauges that show a quarter tank of gas is left even when the tank is almost empty."
http://www.insideline.com/nissan/nis...-vehicles.html
"Standish said that typically "fuel goes down to a quarter of a tank and [the gauge] will stop." He noted there are two causes for the faulty fuel gauge. One is a problem with corrosion on the sensor that causes "an interference with the electronics on the sensor," he said. The other is a mechanical problem "where part of the sensor system will come in contact with the side of the fuel tank," he said. No accidents, injuries or deaths are related to the faulty fuel gauge recall."
This sounds EXACTLY like all of the issues here. There must be a fix for this since they did recall those cars. Maybe just Nissan isn't aware of this issue for the 370Z?