Everything is relative. You can track cellphones that are switched off anyway, because companies like CellSense (http://www.cellsensegroup.com/) make detectors that track moving ferromagnetic objects. While CellSense's sweet spot is prisons, there are others who's use cases are more imaginative.
As always, if you're targeted, you're probably toast no matter what you do, short of going off-grid in a remote but populated area with absolutely no tech on or near you, and cash, no plastic.
As always, if you're targeted, you're probably toast no matter what you do, short of going off-grid in a remote but populated area with absolutely no tech on or near you, and cash, no plastic.