Virgin Racing have designed their car completely with CFD technology, and hence didn't rely on any wind tunnel data, nor did it have testing data at the time of its design process. Based on engine data provided by Cosworth, Wirth engineering decided on a tank size just enough to do a race. The team have however found that when the engine is carefully tuned for performance, it consumes more fuel, putting the team in trouble with its fuel tank size.
Although the team is still working on a new fuel tank that can fit more fuel in the current chassis, both cars have been fitted with new fuel collectors ahead of the Melbourne GP. While this will not make a huge difference, it could reduce the pain the team will be suffering until the new fuel tank arrives, expected by the first of the European races.