A lot is in the drive. Living in South Dakota and visiting , or going anywhere, was a long drive. When you can cruise literally for hours at steady speed with little to no traffic you can put up some big numbers. I learned to use a vacuum gauge from my brother's 67 Barracuda. I could even beat cruise control for gas mileage. To give some perspective, we put over 300,000 miles on that car with the same drive train, trying different combinations. Not as many with my 64 Barracuda, maybe 150,000 to 200,000 miles. 64 and 65 Barracudas have good aerodynamics as do 67-69 fastback Barracudas. Plus I was running a 4 speed. I guarantee you I am not exaggerating the mpg we used to pull, and I can also guarantee you my odometer was closer than any back in the day. I still get in our trip car and cruise 5 hours between stops. My cousin said one of the carbs I modified would get around 30 mpg in the 67 Barracuda 273, 904, 3.23 gears at around 55 to 60 mph. But not many could duplicate the carb, tune, and combination, let alone believe it. I can also tell you the monster 273 in the 64 Barracuda only got 10 mpg not cruising on the highway. The 170 was a blast for what it was, and would easily pull almost 30 mpg on a trip.
