The miles per gallon (MPG) for a 1969 Chevy Camaro varied dramatically depending on the engine size and options. There's no single answer. A small-block V8 might get around
10-14 MPG in city driving and maybe
14-17 MPG on the highway. A larger big-block V8 would likely get considerably less, perhaps only
8-12 MPG in city driving and
10-14 MPG on the highway.
These are estimates, and actual MPG would depend on driving style, vehicle condition, and other factors.