On my bike, the remaining liters gauge is lying by about -1 litre (i.e. telling you've got 3 l left when in fact that's 2 l), if we are to trust the tank capacity given in the specs is real.
The remaining kilometres gauge appears to be accurate down to about +5 km (i.e. telling you've got 1 km left when you have 6 km), taking into account the fact that it's dynamically evaluated from the instantaneous MPG value.
One point to note is that you can never ride a fuel-injected vehicle for as long as you could a carbureted one (i.e. bone dry) because the kind of fuel pump the former uses needs to have some fuel left around its intake to function.
The lowest I got so far was when I refilled 18.83 l (so 670 ml left in tank, if we are to trust the spec) and the gauge said 1.5 l left and 6 km to go. At that time, the orange fuel pump idiot light was steady on, not flashing.