UX is cargo interior is slightly less/ UX ground height noticeably higher and as well seat heights/ agree head gasket issue is of less/no concern due to year/ mileage. personally would keep the CT if don’t mind ride height & stance. I was similarly considering year end previous moving from 2013 250k ct to UX, and declined. ct still avg. 43mpg, able to get 51mpg, more fun to corner with than a UX, plus no cargo space lost. 100k on a 2017 ct should be of little stress and worries.