Strong demand for a number of Chrysler's products means that six of the automaker's North American assembly plants won't participate in a regularly-scheduled two-week mid-summer shutdown.

A quartet of plants in Illinois, Michigan, Ohio and Mexico that build the Dodge Dart, Durango and Journey and the Jeep Grand Cherokee and Wrangler will keep workers especially busy this year because they will skip the shutdown entirely. Two additional plants in Michigan and Mexico will observe only a single week shutdown, while Chrysler's four other plants scattered in the Midwest and Canada will close for two weeks.

Traditionally, Chrysler has idled all of its North American plants for two weeks to update tooling and to reduce vehicle oversupply.

With sales up 33 percent in the United States so far this year for all of Chrysler's brands, the automaker says that its plants need to keep cranking out new cars.