The last car has long since taken its last test lap, and most employees have already moved to a new facility in Yuma.
For the past few weeks, perhaps a half-dozen people have been packing for General Motors' final departure from Mesa, bringing a quiet end to an era when American automotive icons like Corvette, Firebird and Camaro had to do or die on a 5-mile test track in the brutal desert heat.
Today, GM will quietly turn out the lights at its vast Desert Proving Ground in southeast Mesa, ending more than 56 years of operations here. The closure is only coincidental with the financial collapse that pushed GM last week to take the once-unthinkable step of declaring bankruptcy.
Not only have times changed in the car-testing business, but urban sprawl has finally crept up to the Mesa site.
What once was ideal land use for a 20th-century industry is no longer appropriate for the new century's aspirations.
But, oh, what a tale the past century can tell.
Roc Arnett remembers when the Proving Ground was shrouded in secrecy, hiding its operations behind barbed wire and tall earthen berms. It was a special thrill to spot a heavily disguised prototype out on the open road for testing.
"I can remember . . . learning to drive, and it would be sport for us to find those future cars and their test cars going down U.S. 60," said Arnett, now president of the civic and business coalition that will be instrumental in planning the future of the site.
"Back then, U.S. 60 was Main Street (in Mesa). As high-school kids, we'd follow those things - 'Is that going to be a Corvette?' 'Is that going to be an Impala?' "
It could have been almost any vehicle GM developed over the past six decades, including some that never made it to market.
There was the Firebird, a brainchild of legendary designer Harley Earl that first zoomed around the circular track in the mid-'50s. Propelled by a kerosene-powered turbine engine, it had a titanium body and a revolutionary suspension system that eliminated springs and shock absorbers.
A generation later, there was the solar-powered Sunraycer, which set a world electric-car speed record of nearly 75 mph.
Although those technologies never arrived in the showrooms, many of the improvements in GM vehicles first went through their paces in the hellish heat, dust and deliberately miserable driving conditions at the Proving Ground.
Jack Sellers, a Chandler councilman, spent his entire professional career there, including almost 20 years as facilities manager, before retiring.
"The facility played a much larger role in a lot of things that General Motors did than many people realize," Sellers said.
One frequent early visitor was Zora Arkus-Duntov, a GM executive known as the "Father of the Corvette" because he advocated saving the now-legendary sports car when sales faltered in the mid-'50s.
Most of the Proving Ground's work was mundane, such as seeing how brakes, tires and other parts would hold up in the heat. Sometimes, components wound up in other companies' products. The Mesa site helped develop transmissions for Rolls-Royce, for instance.
Employment fluctuated over the years. In the mid-'90s, GM had about 400 employees there, but Sellers said that during peak testing seasons, there could be as many as 1,200 people on site as GM's various divisions sent people to monitor work on their respective makes and models