I checked the manuals. For 2009 and 2010 it says 15.5 gallons, but for 2011 and 2012, it says 14.5. But all 4 years say 55L, so I really think it's a misprint.
Audi R8 V10, 6MT, Ibis White
BMW i3 REx Mega, Laurel Grey
[Retired] BMW Z4 sDrive35i, BMW 335i Coupe