The American College of Emergency Physicians Association is recommending that folks enter emergency contact information into their phone directory on their cell phones.
I have done this on my cellphones and recommend that all roadtrippers do it as well. The easiest way to do this is to create a name: ICE (which stands for in case of an emergency) and can provide rapid information to first responders in case the roadtripper is unable to communicate after an accident or allergic reaction or whatever.
Under my ICE -- I have provided the e-mail address and direct phone number to my wife.
Under ICE-2 I have listed another family member.
For more information about this innovative idea, here is a quick article.