A decade after Mazda's cars disappeared from Ford Motor's factory floors in Michigan, the Japanese automaker is once again building in the United States — this time with compatriot Toyota.

When the first Mazda CX-50 crossovers rolled off the assembly line at the joint Alabama plant in January, they were packed with efficiencies hammered out by the two automakers, both known for their cost-cutting smarts and manufacturing prowess.

For Mazda, restarting local production with help from Toyota's deep local knowledge and reputation for reliability is the game-changer it hopes will jump-start sales in the world's second-biggest market.