What's the actual 2015 HDi diesel fuel tank size?

[Lingo_Berlo]

The actual fuel tank size always confuses me. 

The manual says it's 60 liters, but I've never tanked more than 50L even when getting it critically empty (reserve fully used and fuel gauge dead zero). My record is 51 L when I had driven some 20-30 km with critically empty (the reserve light not just on but blinking after the touchscreen computer says you're empty already).

I find someone claiming it's around 52-53L size. Is it correct?

[Tree]

I've managed to put in 56 litres before but that was a fuel station where the pumps were old and slow.