What happened to gasoline in the mid 1970s?

One thing that I see missing in this discussion (and I don't claim to be an expert on this) is that how octane ratings were determined changed around 73-75. Before that producers has their own systems for making octane claims. The Government standardized how the octane ratings were determined (thus the federal octane sticker on the pump). This meant that consumers could compare apples to apples when buying gas, and you couldn't be taken in by unrealistic octane claims.

The biggest thing that happened was that the cost of gas went through the roof!!!! Sometimes stations were charging as much as 42 cents a gallon!!!! I remember my Dad buying a slant 6 Dart in 75 to replace our V-8 1970 model, and used muscle cars were selling for bargain basement prices. in 1976 I tried my damndest to get $1200 together to buy a beautiful low mileage 440 4 speed GTX from a Plymouth dealership mechanic, but I just couldn't come up with that much...