Ford Motor Co. expects operating margins of about 10 percent in North America this year, down slightly from 2012, because the company expects a greater portion of its sales this year will come from smaller cars that are less profitable than trucks.

Higher costs associated with growing volumes also pinched margins, the No. 2 U.S. automaker said in a presentation prepared for an investor conference on Wednesday. Last year, Ford's operating margin in North America was 10.4 percent.

However, Ford expects a benefit from growing U.S. auto sales, higher market share and better vehicle prices.