Is the warning light illuminated on the gauge?
Yep, sorry. Just trying to decide if there is a potential fault with the computer, or whether you just thought the range was too low compared to the gauge. If the gauge is working correctly I can't see the range showing zero without the light? Trying to get it straight ish in my tiny mind 
Range CAN show zero without the gauge light being illuminated. Example: you have driven it like mad and have avg of 40litres/100 km. You have some 15 litres in tank. Light will not be lit as it comes on with some 10 litres left. When driving still like crazy avg consumtion is still high and after 10 kilometers you'll have 0 range and still 10 litres in tank--> no light.
Gauge light and MID do not communicate together. MID just calculates averages and bases range on an average. Gauge shows actual status of fuel levelk in tank and neither of these are very accurate, especially gauge is not.
Slightly off the topic, I have driven Omegas several times to range 0 and never ever have been able to fill more than 70 litres. Tank is allegedly 75 litres. The only time I have ran out of fuel with an Omega was one with TID (no range display) and it was interesting. Filled 7 litres from canister and tried to start, nothing! Had to fill 15 litres before it started.