* Engine size: The Blazer came with several engine options, ranging from inline-6 to big-block V8s. A smaller engine will get significantly better mileage than a larger one.
* Transmission: Automatic transmissions generally get slightly lower mileage than manuals.
* Condition of the vehicle: A well-maintained engine and properly tuned carburetor will significantly impact fuel economy. Things like tire pressure, overall vehicle weight, and even the axle ratio affect mileage.
* Driving style: Aggressive driving habits will drastically reduce fuel economy. City driving typically yields lower MPG than highway driving.
* Vehicle modifications: Added weight or modifications to the engine or drivetrain will affect fuel economy.
Considering all this, a realistic expectation would be in the range of 8-15 miles per gallon (MPG). You might see slightly better mileage on the highway with a smaller engine and lighter load, but significantly worse mileage in city driving with a larger engine. Anything above 15 MPG would be considered excellent for a vehicle of this age and type. Don't be surprised if it's on the lower end of that range, or even lower, depending on the factors above.
