I'm also looking into these; I know Bergstrom (Austin, TX) was used in 1953 and 1954; I have no information at all about when Brooks (San Antonio, TX) was used. Any details, track maps, years of operations, etc., would be greatly appreciated.
I stumbled across this page when I was trying to find info on Brooks AFB and their supposed track. I live in San Antonio now, and my mechanic here recently told me about some of the "car rallies" (his term) that they had there. I should be in contact with him this week, I can ask him about it and post up whatever I find if you'd like... If anyone knows anything about it, or other driver's events in San Antonio please drop me a line at my email: firstname.lastname@example.org