I end up partway there. When I tried to drive to Navarro from San Francisco, the triangle ended up straight north and stopped at the water of the bay. When I tried to drive to SF from Navarro, I ended up in the desert, with the car but only about 1/4 of the way there. If I walk from there, the car travels with me.
Strange things are happening. I could drive to Redding once and then back to SF, but then tried it again and the destination was SF rather than Redding. Can't go to Redding now. I just discovered the Military Base by walking and am able to drive there. I finally walked to Navarro but seemed to come across a lot more battles than before. I am near the end of the game so it really isn't going to be a big problem. I got to meet the guy at the bridge when walking and that was interesting.