Strange that is is a 50l tank but we can only get 43 or so litres in it!
I’m sure you could get 50l in if you ran it dry, but VW want to give you the option of not coming to a spluttering stop when you hit 0 miles on the MFD. Think if it as a 6 or 7l reserve.
The 50l tank was a reduction from 55l on previous gen because we were supposed to be getting so many more mpg based on the cycle tests.
My Scirocco had 55l (12.0 Gallons) tank and was supposed to be 53.7mpg (combined), giving a range of 644 miles. Reality was I got about 530 miles from a tank to the reserve (10.5 Gallons used/50.5mpg).
GTD has a 50l tank (10.9 Gallons) and is supposed to be 67.3mpg (combined), giving a range of 733 miles. Reality is that I get about 430 miles from a tank to the reserve (9.8 Gallons used/43.9mpg).
I would take that reduction in tank size as faith that VW think we should be getting 60mpg from our GTDs so as not to reduce the range on a full tank. Reality is that like for like, the fuel used to take me 530 miles on my Scirocco, would only take me 461 miles (10.5 gallons @ 43.9mpg) driving the same way. That’s progress for you.