If you're talking about the new Chargers, you're exactly correct. My '70 Challenger originally was Plum Crazy, and, no, the color used on the current Chargers is not right. From the pics I've seen, the company that made up a Cuda package for the Challenger and then painted the car purple did a better job of getting the right shade of Plum Crazy than Dodge did on the new Chargers.

Also, I'm not sure I'd want Plum Crazy on a current Challenger without having at least as much striping as the SRTs have. That would be an awful lot of purple without any contrast. My '70 had a black vinyl top, and that combination looked a lot better than solid-Plum Crazy '70s.