18th May 2015, 11:40
Mid teen gas mileage was totally acceptable in those days for a full size car like this. I had Impalas from 63 to 73 vs a Caprice; better trim is all I saw as a difference. They were comfortable, roomy and had a large trunk. If you were a family or even a group of adults, it was ideal. A great car to take off to the beach or go grocery shopping with that trunk.
I still stayed with 2 door models. Later I went to a 1978 Monte Carlo as I liked the look of them. A new body design then. Of course now it's dated, but it was a good car too. And mileage was still in the teens on it too with a 305 on it. All were reliable and not in shops much at all, except for tires and routine items.
In 74 there was the national gas shortage and many panicked and bought small cars. You waited in lines on odd and even days for gas. But those that kept their cars may have been better off vs payments and buying new cars, often without A/C and not as well built. I think the Impala was a wise choice over more expensive full sizes; even Buick or Olds. A lot less expensive and basic. Once you put air conditioning in, the ride and comfort is there. And less to fix. My opinion anyway.
19th May 2015, 12:22
28 was certainly possible on the highway, under ideal conditions - not going very fast (say 55-60), in flat country, without the air conditioning on. But, yeah, you're right, a safer guess at a normal top highway MPG would be about 25. In overall driving they averaged in the high teens to about 20 in my experience (owning about 5 different examples from about 1980-1990). Surprisingly I got similar mileage from the several Delta 88s I owned at that time. The only standout was one 1982 Caprice with the little 267 (I think) V8 - it seemed to get better mileage on the highway - about 28.