I have heard that boric acid is lethal to spiders. It sublimates so just having it nearby will keep them away.
I may try this for the garage in general as they like the corners and other out-of-the-way places there. For the car itself they mostly like to make webs underneath the car, a bit annoying when I have to get underneath for any mechanical tasks, but thankfully they don’t get into the cabin much.
Also thankfully, this invasive species that my area has plenty of prefers being outdoors: pbs.org/newshour/science/ev … oro-spider