Guys, the gauge is not an absolute measure of how much fuel you have in your tank. Floor it for around 20-30kms, do nothing but redline, and notice how quick the needle comes down. That is the car actually telling u that with your current style of driving, this is the petrol consumption you should expect.
Many times in the three years I've kept the swift, I've noticed the needle actually go up if I adopt a completely opposite style of driving. This is the car telling me, again, that with the way I am driving I should expect the displayed petrol consumption.
The gauge doesn't tell u how many litres you have. The gauge tells u how much mileage to expect with your current driving style. I've explained this 5-6 times before too in this very thread.
Hope this helps (again :P).
Sent from my GT-I9500