A while after I bought my car, in the early 80s, I was playing a strategy board Game called Car Wars, about armed and armored cars. I was designing a Challenger for the game, and I wanted it to follow the real Challenger nomenclature (TA, SE, RT). About the same time I was reading a book on submarines in the Cold War, and I came across the concept of a Hunter/Killer. Thus, I named the car in the game the Challenger HK.
Decades later when I joined c-c I needed a screen name and I flashed back on the Challenger HK.
