anyone know the gas mileage for a 75 Malibu classic?

I looked already in the owners manual, only thing it tells me it has 22 gallon capacity, so yeeah, not sure if it is a 4 or 6 cylinder if it matters.

I have owned my 76 Malibu Classic since it was new.

The Malibu Did Not come with a 4 cylinder engine from the factory.
Some had 6 cylinders but most had either a 305 V-8 or 350 V-8.
Average miliage on mine was 15 in town and 18 on the highway. Of course a lot of this depends on how you drive and what accessories you may be running like power steering, air conditioning, automatic Transmission.
There great cars and very dependable. They were not very popular during there era, however, today they are becoming much more desirable but parts are very hard to comeby.