If you have a smartphone, you already have the ability to let someone know where you are located. On most phones that aren't iPhones that will be an Android phone. Most already have google maps loaded on them so all you have to do is go to the menu of Google maps and share your location. By default, it only shares for a few hours. But you can set that up to be shared until you turn it off or any other time period you care to share for.
If you want crash detection, there are some apps that already do that. You'll probably get some false alerts, but you can cancel those prior to them going out and scaring whomever you set up as your emergency contact.