I have used welding cable in the past with no issues. I have been told that it is not a good idea because the welding cable is not rated for vibration common in a race car. Supposedly the fine strands can break and lower the load capacity. Also finding copper terminals with the right size holes for the studs and bolts used in a race car can be hard. If you want to use 00 wire and need 5/16" stud size, the welding terminals are usually 3/8".