Using high current devices combined with currents through the body made me think. So I concluded with a practical approach where a chassis contact is made for every 50 A with a minimum distance of 100 mm. I could not find any information on the subject so I decided to create a model. Apparently some people hate links on this forum, but I don't want to paste it all here. I would really appreciate some review. See https://vanderworp.org/electrical-resistance-of-the-car-body/.