I am ashamed, I must admit, that it's taken me this long but I've only just now done the legwork on where the car was in relation to her departure location and her intended destination and WOW is it ever an eye opener.
The car was found at the intersection of Valle Vista Rd and Ranch Rd, which corresponds to 75099 Valle Vista Road. The google map search: " 75099 Valle Vista Road, Twentynine Palms, CA, United States " will take you straight there.
It is by all accounts the middle of NOWHERE.
This location is Appx. :
-4.5 miles North East of the main cross streets of 29 palms
-1.5 miles North of the closest suburb of 29 palms proper
The main cross streets (intersection) of 29 palms are themselves Appx. 20 miles North West of Joshua Tree National Park
Doing the math we see that her car was parked at least 2 miles in the opposite direction of travel from her home to her supposed intended destination, which put it in excess of 23 miles from same supposed intended destination.
It is clear that searching for her in Joshua Tree National Park is a fools errand at worst, at best it's a clever but also pathetic ruse to thwart a suspects suspicion.
(an article I just read pointed out that the military base might be the subdivision to the north west so it might not be the opposite direction after all, however since she would have passed Utah Trail by a kilometer or so to get to ranch rd and that is the only road into Joshua Tree National Park from the north, it still seems unlikely she was headed in that direction.)