Over 15 years of Skoda ownership, 3 vehicles and being obsessive about range and MPG I can confidently state that unless there is a fault with the sender you will always have at least one gallon of fuel left when the maxidot drops to zero miles, its their way of creating a fuel reserve. The fuel guage needle will be on zero and the measuring block in VCDS will show + / - 5 litres remaining, the system is incredibly accurate but the display deliberately misleading to give a security margin.
When you brim the tank it will show full and the maxidot range will be that which you would get (assuming driver & journey profile remains as before) if you drove till the tank was empty, we will all recognise that when filling up at zero miles we never ever get the range initially indicated at fill up.
As the vehicle consumes the fuel the guage will drop in a linear manner and the maxidot range will drop in a linear manner until the last 1/4 of the tank at which time the for instance 50 mile "reserve" range will gradually dissapear. For example you fill up & the maxidot shows 700 miles range but you never seem to get more than 600 miles before refilling at "zero miles remaining", you will travel 150 miles and the fuel guage will drop 1/4, the maxidot will show 550 miles remaining, at half a tank you will have travelled 300 miles & the display will show 400 miles remaining, at 1/4 tank remaining you will have travelled 450 miles and the maxidot will show 250 remaining. You will only drive 150 miles before the guage has hit zero and the maxidot shows zero miles remaining, you will in fact have 100 miles of fuel left in the tank.
The above example was to make the numbers easier, you would likely have 60 miles reserve.
Before this CR engine I drove all my vehicles to empty several times, (a couple of times when the sender was faulty) the last time was to establish the true range, when it ran dry I filled it with 5 litres exactly, the fuel guage moved up within the red zone, the maxidot showed 40 remaining miles, remarkable accuracy for an inch or so of fuel at the bottom of the tank, I drove 4 miles to a filling station during which time the remaining miles dropped to zero in 5 mile increments.
Over the years I have nearly always driven 50 miles beyond when the maxidot shows zero miles remaining so it must be hundreds of times, 50 miles is when I start to get anxious, I have gone beyond it an not yet run out aside from my first range test, I think that time it was 85 miles but I was in super eco mode.