I agree with your thought process, BP. I plan for the hike from my office to my home (38 miles), or any place in between, in the event of an earthquake; bridges down, etc. I don't see a need for major planning for BOBs. Here in the LA area, if everyone had to leave at once, no one would get anywhere. Being prepared to stick it out at home makes more sense.
The ability to get home and make use of what I have in the way of supplies is the extent of my vehicle BOB contents.
However, because of the abundance of firearms and the fact that I could encounter individuals along the way that might want to take advantage of the situation (I lived here during the riots), I too have planned for that contingency in my vehicle BOB.
Because the weather is generally mild and predictable, I pick items with my comfort in mind, size and weight not being key issues.