Having not seen that before, it perked my curiosity. So, after some searching... it's called "Arizona Proving Ground" (30700 W Patton Rd) and is owned by Ford. Here's some more info...
http://en.wikipedia.org/wiki/Ford_Proving_Grounds Also... the Volvo proving grounds are a little bit SE (20715 W Happy Valley Rd) and is smaller (also mentioned on the wikipedia page).
And I thought the only proving ground here was GM (SE of Phoenix).
We also have Exponent Failure Analysis straight north of Phoenix. They were the independant test site for the Expedition + Firestone stability tests a few years ago
