Cadillac 1975 Owner's Manual page 4

IMPORTANT FACTS YOU SHOULD KNOW ABOUT GASOLINE MILEAGE AND HOW TO IMPROVE IT
How you drive, where you drive, and when you drive all have an effect on
how many miles you can get from a gallon of gasoline. The careful attention
you give your car as far as maintenance and repairs are concerned will also
contribute importantly to fuel economy.
83. Unleaded gasoline is essential for proper emission control system
operation, and it will minimize spark plug fouling. The use of leaded
gasoline can severely reduce the effectiveness of the emission control
system and result in loss of warranty coverage.
Fuel Selection
Your vehicle is designed to operate only on unleaded gasoline of at least 91
Research Octane. The gasoline should also have a Motor Octane of at least
FIG. 1-1: UNLEADED FUEL OCTANE IDENTIFICATION
If the service station gasoline pump has a symbol similar to that in Fig. 1 -1,
use unleaded gasoline with a symbol number of 2. If the pump has a label
indicating gasoline octane in terms of the average of Research and Motor
Octane [ ] as shown in Fig. 1 -1, use unleaded gasoline with a number
of at least 87.
"lackrabbit" Starts
Gasoline can be conserved (and engine and tire life prolonged) by avoiding
unnecessarily rapid acceleration away from lights and stop signs.
Stop-And-Start Driving
Frequent stops and starts during a trip really cut down on your miles per
gallon. Plan even your short shopping trips to take advantage of through
streets to avoid traffic lights. Pace your driving like the professional drivers
to avoid unnecessary stops.