Fiat SpA is starting to rethink the roles of its multiple brands now that it is about to fully combine with Chrysler Group LLC, starting with the model lineups for its Chrysler and Dodge brands in the U.S.

The Chrysler brand has suspended plans for a small car called the Chrysler 100 for the near term, preferring to focus on its existing portfolio of three models including the Town & Country minivan, a top executive said in an…