The 111" wheelbase also puts this car physically in the same company as TL (109"), ES (109") , MKS (112") etc.
And in case anyone is wondering... Saab 9-5 and LaCrosse also 111". XTS just has a really long rear overhang so there is a big trunk for the golf bags. Or dead hookers.
XTS is basically the 2012 version of FWD Taurus based 1988 Lincoln Continental... mid size platform, fullsize body.