SLANT 6 a GAS GUZZLER?
FWIW, in the fall of 1973 when the new models came out I purchased a new 74 AMC Hornet X hatchback with a 232 3spd manual tranny. Don't recall what the gears were but there was not an optional ratio in the car. My room mate at the same time purchased a new 74 Dart Sport with a 225 and A904. Don't really have any idea on what his car had other than his car cost a hundred or two more.
Anway we were both going from V8 cars to the sixes for economy because we were making several trips a week from the Boston area to the Hartford area.
I know if I was real careful watching my speed on the hiway I could get 30 mpg and once got 34.5 by drafting semi's as much as possible but more typically 28-29. Around town I would get 22-23 mpg. On the other hand my room mate with the Dart could only squeeze 25 mpg out on the hiway but dropped into the high teens around town. I realize it's not apples to apples with the AMC having a manual and the Dart an auto but I would say these numbers were pretty representative of what you could expect.
The other notable difference was the Hornet would easily out run the Dart in a drag race.
A few years latter I needed a pick-up and picked up a 74 D100 short bed with a \6 and A904. This was a stripo with rubber mats and no radio. I have no idea on gears but they were not extremely high (didn't scream on the hiway) or extremely low (decently peppy off the line). The truck would get 13-15 around town and I had to be real careful to get it to 20 on the hiway.