It was 102 octane.
http://en.wikipedia.org/wiki/Sunoco
In 1969, it was around $.36 a gallon in Detroit.
When I cruised Woodward Av. with my friends, it cost less than $5.00 for a tank of gas, which would take you less than 100 miles. If you were a kid who worked for the minimum wage, $1.50 an hour, that was just over 3 hours wages to cruise on Friday night.