misd-agin, you are totally right.
The 4000NM is meant as operational range, with a usefull payload, winds, diversions, reserves. The official no winds, only passengers, sealevel take-off, long runway range would be significantly more.
The brochure range for the new A321 NEO with GTF's will probably be around 3700NM, its operational, usefull range significantly lower..
btw the fly is to make sure everyone sees it's all un-official 