The Lightweight Concept started life as a 2013 Ford Fusion, but lost 25% of its weight through the use of high-strength steel, aluminum, magnesium and carbon fiber.
The resulting vehicle — about 900 pounds lighter than a standard, 3,600-pound Fusion — weighs about the same as a Ford Fiesta, an economy car two classes down the Ford lineup. Ford expects that the weight loss will translate directly into fuel efficiency gains.
"This is a mid-sized sedan with the fuel efficiency of a very small car," said Matt Zaluzec, the Ford executive responsible for global materials and manufacturing research.
All automakers are trying to cut weight to save fuel, but few are pursuing the strategy as aggressively as Ford. Cutting weight can have a big effect on efficiency because it enables smaller engines to produce the same performance.
Indeed, Ford installed its tiny 1.0-liter, three-cylinder engine in the Lightweight Concept. The same engine is rated at up to 45 miles per gallon in the much smaller Fiesta hatchback.
So far, Ford has built just six of the Lightweight Concepts, and they aren't for sale. But the automaker has already made a huge bet on weight-saving technology with its latest Ford F-150 pickup, the bestselling vehicle in America. The truck, redesigned for 2015, shed 700 pounds through extensive use of aluminum throughout the body.
The aluminum enables the truck to "tow more, haul more, accelerate quicker and stop shorter, with improved gas mileage," according to Ford.
Using aluminum on such a high-volume seller will help Ford bring down the price of the technology for wider use.
"We're making the jump from low-volume to high-volume vehicles," Zaluzec said. "You'll start to see aluminum ... migrate to other products too."
Ford would not say when a lightweight Fusion might make its way to showrooms, nor at what price. The standard Fusion starts at $21,970, about $7,000 more than the much smaller Fiesta.
Ford apparently is committed to the weight-saving strategy, said Don Anair, research deputy director of the clean vehicles program for the Union of Concerned Scientists.
"Automakers have a number of strategies for increasing fuel economy, and lighter-weight materials is one of the key strategies," Anair said. "Ford has been showing some leadership there."
One key advantage: Saving weight in one part of the car makes it easier to do so elsewhere.
"A lighter vehicle allows you to use a smaller, more efficient engine," Anair said.
Ford also systematically shaved weight from other areas in the concept Fusion.
The suspension and braking systems, for instance, lost 30% of their weight through the use of aluminum brake rotors, along with hollow steel springs and stabilizer bars. Ford then installed skinny carbon fiber wheels, at 19 inches tall but just 5 inches wide.
The interior lost 35% of its heft, in part by using carbon fiber seat backs and interior components.
The powertrain lost 24% of its weight with the use of an aluminum engine block, hollow steel crankshaft, and aluminum and magnesium transmission parts.
Carbon fiber parts also show up in places like the oil pan and engine cover. New methods of composing glass for windshields have also helped shed weight.
But the lightweight effort comes at a cost, particularly in the case of Ford's popular pickup. Ford has spent huge sums of money developing the aluminum replacement parts, and the systems for assembling them, without knowing whether consumers will embrace a lighter truck.
"It'll get better gas mileage, but the question is whether or not they can sell it as something that is as rugged as the historic F-150," said auto expert Aaron Jacoby, an attorney with the Arent Fox law firm.
"Everyone is trying to find a recipe to achieve better fuel economy numbers, and Ford is trying to do it by light-weighting," said analyst Dave Sullivan of AutoPacific Inc. "This is their highest-volume vehicle, so it has to work. Billions of dollars are at stake."