Screenplay writer Nick Schnek first thought of the idea for Gran Torino in the early 1990s, when he worked at a VHS factory in Minnesota and befriended Hmong coworkers. The process between writing and selling his script was a long one, and it wasn't until Clint Eastwood got on board that the film could be made.
Eastwood loved Schnek's script, claiming that he "didn't change a single syllable" in it. Eastwood has said that he felt any changes to the script would "emasculate" it, thereby cheapening the movie. Eastwood was drawn to the story because "it dealt with prejudice, [and] it was about never being too old to learn." When filming for his movie Invictus was pushed back until 2009, Eastwood could direct and star in Gran Torino.
Although originally inspired by Minneapolis, Minnesota, Eastwood decided it would be best to shoot the film in Detroit because it would take advantage of a significant tax credit in addition to the rich Hmong heritage in the state (something that Minnesota also had). Eastwood decided that because Walt was a retired autoworker, Michigan would be a better area to set the film in.
Gran Torino was the first mainstream American film to prominently feature Hmong Americans in its story. Eastwood's casting director filled the substantial Hmong American roles through open casting calls distributed among Hmong communities in Michigan, California, and Minnesota. On set, much of the Hmong-language dialogue was improvised by the actors, the script having been written in English.
While the film hired Hmong-American cultural consultants, the film has been the subject of criticism. Hmong-American critics have cited cultural inaccuracies in the film, arguing that it overly exaggerates and exoticizes elements of Hmong culture. Among many other examples, critics have pointed out that the Hmong don't lavish people with gifts and offerings the way they do to Walt, and most Hmong people would not find touching a child's head to be anywhere near as taboo as it is depicted in the film. One of the most prominent denouncers of the film has been costar Bee Vang, who has said that the plot does not have much to do with the particularities of Hmong culture.