North American auto makers’ decision to lower reliance on sourcing vehicles from overseas plants is fortifying the North American production outlook, despite signs growth in demand, and the economy overall, might be slowing.

WardsAuto expects nearly 15 million light vehicles to be assembled in North America in 2012, increasing to 15.3 million in 2013.

The 2012 outlook of 14.98 million light vehicles is an increase of 17,000 units from a WardsAuto month-ago update and marks a 14.5% increase compared with 2011, while 2013’s total represents a 2.1% year-on-year gain.

Recent announcements of new plant investments by Japan-based auto makers reconfirm the moves by most manufacturers to locally source more of their products in their major markets.

Sales in North America are reflecting a greater the mix of domestically produced vehicles in recent years. That will continue to do so as long as the U.S. dollar does not radically strengthen against other global currencies, particularly the yen and the euro.

Nissan, Honda and Toyota each announced moves in the last month that point to more local sourcing to meet North American demand.

Nissan will ease a capacity bottleneck by adding output of its Sentra small car to a second location in North America. The redesigned ’13 model, set to begin production at the auto maker’s Canton, MS, plant in December, currently is built in Aguascalientes, Mexico.

Without this move, Nissan would have been unable to meet demand for its cars until a new factory opened in Aguascalientes, Mexico, late next year. The auto maker also is expected to source its Murano cross/utility vehicle locally for North America for the first time beginning in 2014 when the next-generation model is due.

The likely locale for Murano output is the Smyrna, TN, plant. That shift will add roughly 70,000 units annually to Nissan’s North American production.

WardsAuto expects that by 2014 more than 80% of Nissan’s North American sales will come from locally assembled vehicles, compared with 71% this year. Sales of vehicles built in the region eventually should surpass the 80% peak Nissan hit in 2005-2007.

Honda’s is adding capacity for both the Civic small car and CR-V compact CUV that will lead to more import replacement. The auto maker plans to increase annual straight-time capacity at its Greensburg, IN, plant by 50,000 units in 2013 for a total 250,000 units.

Added capacity at the facility, which also builds the new Acura ILX sedan, will be aimed at more Civics, which also are produced at its two plants in Alliston, ON, Canada.

However, Alliston 2 has not built any Civics since March. Production has gone almost entirely to the CR-V in that time, while Alliston 1, save for small volumes of the Canada-sold Acura CSX, is devoting its line to nearly all Civics.

Honda can re-introduce the Civic to the Alliston 2 mix at any time, but for now it appears it will source CUVs solely from the plant, reducing the number of imports from Japan and perhaps ultimately phasing out overseas sourcing. CR-Vs also are built for North America at two other Honda plants in the U.S. and Mexico.

Honda’s sales of locally made vehicles are on pace for a company-high 89% of its North American sales in 2012 and should top well over 90% in 2013. That number will continue to climb after it opens a new plant in Celaya, Mexico, in 2014 to build the Fit compact car.

Toyota, whose sales in North America contain the lowest mix of locally built models among the top volume auto makers, will begin sourcing all Highlander SUVs locally in 2013 when it adds the hybrid version to its Princeton, IN, plant.

Toyota sales will reach a 70% mix of locally produced light vehicles this year and should see that grow slightly in 2013 and again in 2014, when it makes a small increase to its 30,000-unit capacity for Lexus RX luxury CUVs built in Canada.

The majority of RXs sold in North America are assembled at the Canada plant, and the additionally capacity could mean all of the CUV’s regional sales eventually will be locally sourced.