GLA - is the boot really 480 litres?

[havoc]

As above. Just been to look at one as a more practical replacement for the wife's Golf GTI, and the boot looks pretty similar to the (380 litre) Golf.

Certainly isn't as big / bigger than the +/- 450 litre boot in my car.

So I'm confused. Are they measuring it differently / has there been a change recently, or is this another example of car manufacturers coming out with new ways to measure things and the press not checking?

Tried googling but nowhere (even Merc's own brochure, fully) is giving me boot dimensions...

Thanks,

Martin.