I think I ended up using #0000 cable to run from the back of the car, in the spare tire well, to the front of the car, where it entered the controller cabinet.
I didn't mention the size in the video, and the cable is scrap from where I work. The numbers are rubbed off the outer jacket. Scrap cable is about 15% of the cost of new cable. I know the history on this one, and it is only 5 years old. It was removed to increase the size of the motor so I am confident it has many years of service left.
https://youtu.be/Lkt5vGDfkEM
Measure twice, cut once ... but PAY ATTENTION when measuring so the darned cable, with it's 14 inch bend radius, will get past things like rear brake fittings. It took an extra day to fabricate a patch for the first hole, drill the second hole, and get the patch riveted in.
The cable, called teck cable, is 3 conductors of #0000 with 1000V insulation plus a #2 ground in a pvc sheath with aluminum interlocking armor around it, and a final plastic jacket. Big, beefy, doesn't bend well. But it didn't really need to bend much ...