That is already a bit better than pre-LCI Cooper S. I had a 2007 Cooper S that was averaging 8.5l/100km.
I am now averaging 5.55 in an SD, so I doubt you'll see 5.6 unless going downhill with a tail wind.
I don't think anyone gets the published figures. Most Minis leave the dealer with fat tyres that are more fun to drive but definitely not good for fuel economy.
Just enjoy guys and know that it is still the best performance per $ car out there