Redundant? Your vocabulary or your mechanical sensibilities are not up to their usual high standards. Actually, I'm sure it's your mechanical sensibilities, since you've demonstrated your command of the language. Those six spark plug wires, none is redundant.
Oh. You were following on from SD's remark. Nevermind. Still, redundant...
SD: One per spark plug, since they fire independantly. Six cylinders, six plugs, six wires.