Six years ago, Ford's Michigan Assembly Plant was a relic, emblematic of a creaky Detroit auto industry on the verge of collapse. Workers at the 50-year-old facility produced the gargantuan-sized Ford Expedition and Lincoln Navigator during the heyday of America's fling with big SUVs. When fuel prices spiked and ended that craze, the plant's fortunes, and those of its workers, plunged.

Instead of shuttering the facility, Ford transformed it into a model for its future. On Thursday, the automaker hailed its arrival with a 21st century product built for fuel economy instead of vanity or brawn--the C-Max Hybrid and C-Max Energi, an extended-range electric vehicle.

See our review of Ford's C-Max here.

Intent on building a manufacturing strategy that could reflect customer demand in more accurate fashion, Ford turned the Michigan Assembly Plant into the world's first to build gas-powered, electric, hybrid and plug-in hybrid vehicles simultaneously on the same assembly line.

The much-ballyhooed C-MAX models began rolling off the lines here earlier this month. Ford had already built its Focus, Focus ST performance car and Focus Electric here. Four of the five vehicles produced here earn 40 miles per gallon or more, making the assembly plant a model of fuel efficiency.

But the fuel-efficient shift isn't necessarily what has Ford executives most excited about the $550 million rehabilitation of the plant, located along Michigan Avenue not far from its Dearborn, Mich. headquarters. It's the ability to adapt to fickle consumer demand almost down to the minute.

"We want to be able to respond to the market if it's up or down, and not be trapped with dedicated one-trick-pony plants where you have under-capacity or over-capacity situations," said Jim Tetreault, Ford's vice president of North American manufacturing. "It's very rare you can say 'this is the demand in 2013 for that vehicle' and hit it exactly right."

He said Ford specifically wanted electric and gas powertrains on the same assembly line so it could avoid situations like the one General Motors recently faced, when it temporarily halted production of the Chevy Volt amid flagging demand.

While consumer demand for hybrid and newer all-electric vehicles has shown an upward trajectory over time, short-term demand has fluctuated amid changing government incentive programs and up-and-down gas prices.

"We wanted these electrified powertrains on the same line, rather than dedicated electric lines, so we could assure that whatever the customer decided they wanted, we'd be able to built it," Tetreault said.

For Ford, that approach is the wave of both the future and present. All five cars made here are built upon the company's C-platform, but the plant, first opened in 1957 to produce Mercury station wagons, is now capable of producing cars made on two different platforms. Already at Ford's Louisville Assembly Plant--where the Expedition moved--six vehicles are produced in similar fashion on three different platforms.

Other automakers have run multiple models and platforms on the same lines, but never before with such varied powertrains. In the world of manufacturing, it's a major achievement, one that took Ford more than four years of planning and employee training.

Despite their common C-platform DNA, there are 1,074 different parts between the Focus and C-MAX and 604 work stations that needed to be configured along a line that snakes three miles through the 5-million square-foot building.

The 5,170 workers here must be prepared for whatever comes down the line. In chassis, for example, plastic fuel tanks are stored on one side and electric chargers on the other. Several stops down, other workers attach either battery packs or exhaust systems, depending on the vehicle.

Ultimately, the co-mingling of different models allows the company to both utilize its capacity better and reduce its operational costs. Bill Frykman, a Ford manager of business and product development, said the company saved 30 percent of operational costs at Michigan Assembly because the Focus and C-MAX shared the C-platform.

Reinvestment into the lines at Michigan Assembly, combined with Ford's decision to move assembly of the Ford Fusion from Mexico to Flat Rock, Michigan earlier this year has meant an increase in 5,200 employees in the company's U.S. workforce this year.

It has been a huge victory for Michigan specifically, which had otherwise seen Saturn, Pontiac, Mercury, Plymouth and Oldsmobile fold over the past decade. Could more good news be on the way? Tetreault was tight-lipped about whether a second platform could eventually be added at Michigan Assembly. "It depends on the market," he said.

Not long after, he said Ford is operating at 114 percent capacity right now throughout its North American operations. Automakers expect to sell 14.9 million cars this year, collectively their best year since the Great Recession struck, but still significantly fewer than the 17 million sold at the industry's all-time high. How will Ford stretch production should the market rev up again?

"Stay tuned," Tetreault said.