What happened to gasoline in the mid 1970s?

Sunoco pumps were grades 190 to 260.
I think/remember 260 was the industry high at 112 octane.
Cost -
190 was 24.9 cents per gal
260 was 44.9 per gal
Fuel trucks dumped 190 and 260 and the pump did the 'blending'

A brand new loaded 340 A-Body = $3500.00