National Geographic has a series called Ultimate Factories, and in this 2011 episode they took a close look at the Brampton, Ontario plant where the Dodge Challenger is built, along with the Saltillo, Mexico plant where the Hemi is built. The Challenger, which shares the line with the Charger and 300, takes just 20 hours to go from raw steel to a running, driving Mopar. Watch the entire process in the 45 minute episode after the jump!