Battery ground wire and hot wire section

I probably should let this go because I don't really have a dog in the fight. For those of you who use your frames as grounds you may wish to compare steel and copper in the attached table. Clearly copper is the better choice.
Electric Resistance – The Physics Hypertextbook
Steel 1.68E+06
Copper 1.66E-08
Simply put, steel has 14 times more resistance than copper.
I have used #2 welding cable on three cars ( have it on my 505" barracuda right now) when moving the battery to the trunk, and used welding cable on 4 diff. cars. I have never ran a full length ground cable on any of them, and never had a problem w/ any of them. II f # 2 is getting hot, something else is wrong. I do however have have a motor plate and extra grounds located in various places thru out the car. My motor plates have always grounded the engine successfully. ?????????? who kjnows ?