Excess Wiring

If it's a more modern car, especially one with CAN bus, just leave the wiring alone. Tuck the extra out of the way and ignore it. Saving those 2 pounds from trimming wires isn't going to gain you anything compared to the nightmare that is the car being angry because you cut the nervous system.

Our saab wouldn't even let us remove the onstar controller. Forget that it hasn't had onstar activated in a decade, unplugging the controller pissed it off real good. It still complains that the CD changer was removed without being "unmarried" from the car. Every time we turn it on it goes through about 8 warning/error screens about all the broken or missing systems.

Just leave the wiring alone.

Wise words from the voice of experience. If you get a few races in and you feel like an extra 30 pounds of wiring in the car are what's holding you back, then spend a weekend or seven tracing wires and removing them while being fully aware that the CAN-bus might absolutely lose its shit and kill the car if a door sensor wire is gone.

I might also recommend you go find a hammered 1980s Volvo 240 instead of whatever you've found. They have like seven wires and a long wheelbase. Awesome starter Lemons cars and you can still find them for pretty cheap AND find parts cars in junkyards (at least around Chicago).

Our 735i came with an optional fax machine, wine cooler, and gobs of other weird luxuries that I'm too poor to comprehend. We have 2x 5-gallon bucket sized balls of mystery wiring in the backseat and and a third ball where the dashboard used to be. The dashboard ball we zip-tied into a tighter ball, and the rear seat wireballs we tucked into the butt-wells that were the rear seats and covered it with a piece of plywood. IMO, the wires will only be a problem if someone is stepping on them, breaking them, and shorting them out... hence the plywood.