It's also said there that Renault uses the casting method with water to determine the boot content. Measured according to the VDA method, the boot would certainly be smaller.
Casting is known as an indirect or substitutive method, The VDA method most commonly refers to the German Automobile Industry Association's (Verband der Automobilindustrie) method for measuring cargo or boot volume by filling the space with standardized 1-liter blocks (measuring 200x100x50 mm), counting them, and converting the total to cubic meters. This method provides a realistic, usable volume by excluding small gaps.
Since (I think) we rarely transport (unpacked) liquids in the boot the VDA method seems more realistic to me.
