A lot of bad information has been posted here.......
The only thing "police" get when you use a cell phone for a 911 call is your name and phone #. Period! And that even depends on the carrier. Your GPS can NOT be used by Police to locate you untill they have obtained a court order 'warrant' allowing them to do so then that gets to the carrier and by that time, your cell phone battery will be dead.
If your worried about it, the very best thing to do is to tell a friend or family member of your route of travel plan so that if you do go missing, someone will have a good idea of the area or route you were on.
GPS on your phone was not designed to be a "police" emergency tool. It is a huge mistake to rely on it in that manner..... IT WILL NOT HELP YOU THAT WAY.
Jason