Found these wiring holders in a junk drawer. I used these to organize wires in a former home theater project.
Not sure if they will hold up in the long run for a car application, since they have to endure vibration and varying temperatures. I'm trying them out anyway.
With this being my daughter's car, she doesn't need to have to do anything but deal with getting the spare out of the car, and not traverse though that wiring mess.