Oldtimer here too. I remember those "gas wars". I don't remember it going to 12.9 but I do remember it at about 18.9. We could ride all night on .50 cents worth of gas. Oh, and BTW you could get oil for about .10 cents a quart and most of us needed it because those old cars burned oil like it was water.
I worked at a cut rate station back in late 65 early 66. 18.9 was the going rate at APCO in KCMO at that time. We would occasionally get in a war with a Hudson station up the street and the price would come down for a few days. My parents home at the time had at least 8 service stations within a mile. Today there are 2.