But, if it reaches a point that you decide to leave the vehicle behind and hike out, leave a note for the search and rescue team. The note might even be spotted by a ranger or some other individual before a search has been initiated. Leave the note on the dashboard where it is protected from the elements.
On the note, include your name and information about the type and color of clothing you're wearing, equipment you have with you, how many are in your group, which direction you plan to travel, etc. Give authorities as much information as you can to help them find you.
Also mention your medical situation — whether you (or anyone in your group) are sick or injured or in need of prescription medication. This will help the rescue team be prepared to render medical assistance when you are located.
Don't take off across country thinking you're taking a short cut to civilization. Follow the road or trail that you drove in on. Your chance of encountering someone who can help you is far higher if you are on the beaten path. And your chance of getting lost and/or injured increases dramatically if you leave the road or trail and start hiking cross-country.