My mom and Dad, when in their 80's, still drove. They had car chargers and even gave me one because I usually charged at home only. I guess it depends upon the person. But since they both are diabetics and have other health concerns as well, I assumed they would have a car charger on a long road trip. JMO
IIRC, it was reported in MSM
That their phone was off coming out of the casino. Their daughter was told by LE that the phone pinged off the casino tower, so it must have done that while off, just a ping, then once more off the tower by the highway, within fifteen minutes of their leaving. Coverage seems spotty even in Valley Center unless there is a direct line of site to the nearest tower.
The two of them, in the still shots released both seem in distress, Mr. Knutson has a cane and all Mrs. Bedwell-Knutson has a jacket or something over her shoulder, no purse that I can make out. They're walking apart, looking distressed, both of them.
Contrast that to the description given of them by their neighbors, which is more vibrant, by their children expectations, who waited for them and the dessert they were bringing with them for the BBQ after their stop at the casino, which they were said to frequent at least monthly, so very familiar to them, normally.
That the signal from their car GPS and phones all stopped after that last ping could either mean they flipped their car over somewhere where signals can't reach, or the other possibilities, given what's seen and how the search for them has progressed so far.