I FOUND VAULT 13 IN REAL LIFE!
After heavy calculations and three attempts to post, I found it.
Each of the cubes on Fallout 1/2s maps is equal to 12 miles in any direction. There are twelve of these cubes between Vault 13 and Necropolis. 12 × 12 = 144, and I found a city that is 141 miles and a Two Day walk from Bakersfield into the northwest.
Now, you may notice that there are three extra miles on my calculations. This is because Vault 13 resides on the Northwest Outskirts of this city I have been led to believe is the location of V13, and a walk through this city Southeast would likely start with a 3 mile walk through the ruins.
Finally, after 30 years of speculation, disproving and hope, after suggestions of The Inyo, Death Valley and other areas, I have concluded one thing:
Vault 13, which started it all, is located on the Northwest Outskirts of >!Fresno, California.!<
Edit: You realize that Bakersfield also isn't in the mountains, yes? Maps can prove it.