FLAT ROCK, Mich. - One of America's best-selling cars is now being built in America.

FLAT ROCK, Mich. — One of America’s best-selling cars is now being built in America.

Ford Motor Co. said production of its Ford Fusion sedan began Thursday at the company’s Flat Rock Assembly Plant. Previously, all Fusions were built at a Ford plant in Mexico.

At Flat Rock, the Fusion will share an assembly line with the venerable Ford Mustang, a car closing in on its 50th anniversary.

Ford spent $555 million at the plant, adding a flexible body shop that allows multiple vehicles to be produced on the same assembly line, and updating its paint shop.

“We have completely transformed Flat Rock Assembly Plant to help prepare for Fusion production,” Flat Rock Plant Manager Tim Young said in a statement. “These upgrades have allowed us to ensure we are building the highest-quality cars.”

The addition of the Fusion brought 1,400 new jobs to the plant, which builds cars on two shifts. Ford said Thursday the plant employs about 3,300 people, 3,100 of whom are hourly.

Flat Rock is in Wayne County, about halfway between Monroe and Detroit, about 35 miles north of Toledo.

The automaker has been working to build more flexibility into its assembly plants, enabling the company to better respond to market conditions. Being able to build more than one vehicle on the same line allows Ford to quickly adjust its production numbers to match dealer orders.

“Before if you didn’t have any orders, the plant was idle,” Ford spokesman Kristina Adamski said.

Ford stole the show at the 2012 North American International Auto Show in Detroit with the redesigned 2013 Fusion.

The sleek sedan also has been a hit with the buying public, so much so that Ford couldn’t build enough to satisfy demand.

“Fusion has exceeded all of our expectations, with demand outstripping supply,” Joe Hinrichs, Ford president of the Americas, said in a statement.

The company said the addition of Fusion production in Flat Rock will bring Ford’s total annual capacity on the vehicle to as many as 350,000 units.

The 2013 Fusion went on sale last fall. Ford sold 241,263 Fusions last year. Sales have been better this year. Through July, Ford has sold more than 181,000 Fusions, up 13 percent.

“It’s been a great seller. It’s an awesome car,” said Rob Whitner, general sales manager at Brondes Ford Toledo.

Mr. Whitner said the Fusion has helped Ford compete against Honda and Toyota, both of which have very strong, well-established vehicles in the segment.

Being able to now say the Fusion is American-made will give the dealers a little more ammunition as they try to move them off their lots.

“I think it’s a good thing,” Mr. Whitner said. “I think it’ll help the reputation of the car a little bit.”

Ford says most Michigan-built Fusions will be sold in North America.

The Fusion Hybrid and the Fusion Energi plug-in hybrid will continue to be produced exclusively in Mexico.

Contact Tyrel Linkhorn at tlinkhorn@theblade.com or 419-724-6134.