Only ten 1966 Plymouth Belvedere II convertibles left the factory with a 426 Hemi, six of those with automatics, and just one in the color code 661 Metallic Mauve — the car in this episode, restored with its original numbers-matching driveline intact. Commenters can’t agree if the color is mauve or purple, but they agree on one thing: this Hemi was built to be feared, not casually enjoyed. What actually makes a car the rarest piece in a collection already built around rare Mopars?