Miniatures Were Used In Filming
The Charger shortage became even more of a problem when there was a shortage of AMC Ambassadors as well. The Ambassadors were being used to supplement the shortage of Chargers and when that wasn’t enough the producers decided to use miniatures to get the job done. There are certain scenes in the show that used Hollywood magic to look realistic, but the reality was that it was a toy (via Road & Track).
This is something that a lot of movie studios do even now, but it was greatly exacerbated by the fact that the Charger was in a limited production run. The use of miniatures helped the show to stay on the air and relevant. But fans still remember the show for the real production car that appeared and starred in it.