The fifth-generation Subaru Legacy was originally unveiled as a concept car at the 2009 North American International Auto Show in Detroit to commemorate the 20th anniversary of the model, and the production version was introduced at the 2009 New York International Auto Show. Production of the fifth generation started on 29 May 2009.

The Subaru FA engine is a gasoline boxer-4 engine used in Subaru and Toyota automobiles. It is a derivative of the FB engine, with efforts to reduce weight while maintaining durability as the main design goals. Although the FA and FB engines share a common platform, the FA shares very little in dedicated parts with the FB engine, with a different block, head, connecting rods, and pistons.