Most Barths are automatics...
Any advantage for standard
6 (or?) on the floor???

besides not getting fat and lazy?

Having driven straight trucks back in the 70's, I can see a lot of advantage to a stick when cruising through the mountains or even a hilly area, but in the kind of traffic around a NASCAR race or Buc's game, it would be a nightmare on the left foot. I would think you'd pick up a mile or two in gas savings, based on a 454 gasser. As for diesels, someone else will have to answer.