I'm with the Depends Camp, if I were replicating one of the vehicles I've owned or building a vehicle "inspired" by the ones I've owned (since the only one of them have been offered as a model of some sort ), the wires would need to be blue since I've run either Talyor or Mopar (which I think were made by Taylor anyway ) wires on them. I'd also have to use black, white, orange, candy blue, or safety yellow on oil filters too for the same reason. If I were replicating a factory fresh car, black might be right, if I'm replicating a specific modified car, then the wires should be the same color as what the prototype has. Now if it was a fantasy hot rod of some sort, I'd go for wires that worked with the type of car (street rod, specialty shop style custom, or true Kustom might get a color matched set while a regular street machine might get Yellow, Red, or Blue wires). If I were to get creative and were building a beater, I'd mix and match things like that, wheels and tires, body panels, or other similar, removable and junkyard source-able parts