"The comments we were getting from China was that our original design was too dark, too sinister. So we changed the whole construction," said Chris Hamilton, who headed up the exterior design team for the Fusion.

The design changes on the 2013 Fusion are an illustration of how the No. 2 U.S. automaker is going to great lengths to fulfill Chief Executive Alan Mulally's "One Ford" plan.

Mulally's mandate, which has been a centerpiece of Ford's turnaround since 2006, is to unify Ford's once-disconnected business units and take advantage of its scale to drive down costs and build a global brand.

The family-sized Fusion, which debuts at the Detroit auto show this week, is the third Ford vehicle to get a global overhaul after its smaller stable mates, the Fiesta and Focus.

With the Fusion, Ford takes aim at a segment of the U.S. auto market dominated by the Toyota Motor Corp Camry and Honda Motor Co Accord.

Both the Camry and the Accord have somewhat lost their cache in recent years hurt partly by fast-rising entrants like the Hyundai Motor Sonata.

Last year, Fusion outsold the Accord, but fell behind the No. 1 selling Camry. The new Fusion, which boasts a more athletic design and more fuel economy options, offers Ford a chance to gain ground in this bread-and-butter segment.

"This market, coming out of this recession, is wide open," said Art Spinella, president of CNW Research, which tracks consumer trends in the auto industry.

The Fusion is stocked with features including a system that parallel parks the car automatically. It comes in three gas powered versions, a hybrid and the Fusion Energi, a plug-in hybrid that Ford says can get 100 miles per gallon.

Ford has also improved its MyFord Touch entertainment system. In October, Ford fell ten spots in a key reliability survey due to glitches in the system.

In the updated version for the Fusion, the text is larger, the screens are clearer and the touch-sensitive areas look more like buttons.

A decade of study went into developing the Fusion, said Hau Thai-Tang, executive director of global product programs.

In readying the Fusion, Ford engineers honed in on details as minute as the sound of the closing door to get the precise thud consumers associate most closely with quality.

To find that sound, Ford recorded the various car doors closing and asked people to rate which sounded best.

"We don't have our Wolfgang Puck that says this tastes right," Thai-Tang said, referring to the Austrian celebrity chef and restaurateur. "We do research."

By Deepa Seetharaman

Stocks treated in this article : Ford Motor Company, Toyota Motor Corp., Honda Motor