Ford produced 2.8 million light vehicles in North America last year and output has advanced 13 percent this year through April.
"Approximately 75 percent of our plants are running at a three-crew, three-shift or four-crew pattern in order to ensure we're getting more of our products into dealerships," Tetreault said.
Ford said the plants that will be shut down for one week this summer are in Chicago; Louisville, Ky., Wayne, Mich.; Oakville, Ontario; and Cuautitlán and Hermosillo, Mexico.
Routine maintenance and model-year changeovers are scheduled at Ford's truck plant in Dearborn, Mich.; a car plant in Flat Rock, Mich.; a Kansas City assembly plant; the Louisville plant that assembles the Ford Escape; and a truck plant in Avon Lake, Ohio.
Ford, which plans to hire nearly 3,500 workers this year, said it's three quarters of the way toward its plan to create 12,000 hourly jobs in the United States by 2015.
The automaker added more than 8,000 hourly and salaried positions in 2012.
GM does things 'differently'
GM spokesman Bill Grotz declined to comment on summer production schedules for specific plants. He said GM "does things a bit differently" than in the past, when most plants would be idled for the first weeks of July for model-year changeover and facility maintenance.
"Today, plant downtime is driven more by specific vehicles' life cycles and in market demand," Grotz said.
Still, most of GM's 14 assembly plants in the United States and Canada likely will be idled for at least two weeks this summer. One exception could be its plant in Lansing, Mich., where GM's full-sized crossovers -- the Chevrolet Traverse, Buick Enclave and GMC Acadia -- are built.
Combined sales of the crossovers, which were restyled for the 2013 model year, were up 11 percent through April. GM's overall U.S. sales through April have risen 10 percent.
The company boosted North American production 5 percent in 2012 to 3.2 million vehicles. But with truck model changeovers, production through mid-May this year declined 4.6 percent to 1.2 million vehicles, according to the Automotive News Data Center.
Chrysler said today it will keep three assembly plants open all summer: Jefferson North, where the Jeep Grand Cherokee and Dodge Durango are produced, Conner Avenue, where the Viper is assembled, and Toledo North, which is ramping up production of the 2014 Jeep Cherokee.
Four of Chrysler's assembly plants will be down for a single week this summer: Toledo Supplier Park on July 1; Belvidere, Ill., and Toluca, Mexico on July 15 and Saltillo, Mexico on Aug. 5. Other Chrysler assembly plants, including its two in Canada, are scheduled to observe traditional two-week shutdowns this summer, Chrysler said.
In addition, only one Chrysler transmission plant, Indiana II in Kokomo, will have a one-week shutdown. All of the automaker's engine and transmission plants will continue to operate without a shutdown this summer, Chrysler said.
Chrysler Group's U.S. sales rose 9 percent through April compared with the same period last year. The U.S. market is up 7 percent.
The automaker's North American light vehicle production actually fell about 2 percent, or about 20,000 units, through mid-May because of the end of Jeep Liberty production. Last year, Chrysler boosted production in North America by 19 percent to 2.4 million vehicles, according to the Automotive News Data Center.
Larry P. Vellequette and Mike Colias contributed to this report.