When I did drive far on the highway I was getting 31-33 mpg. 2013 Cruze LT Auto. 1.4L Turbo. Most constant 70mph. I am getting 29 city but haven't driven far on the highway since replacing my spark plugs.
Best I've observed was 56.7 mpg on Interstate 20. It was probably actually a little higher than that because I had to go through stop and go city traffic to get there.
Once I got on the Interstate I averaged about 60mph. Little hills. Nothing steep or long.
I just registered 59.4 for my highest average for 50+ miles but I usually get 55 highway and 44 city. For the speed, I go with the traffic flow in Southern California. Doesn't seem to matter with A/C on or off. Incredible mileage.
2014 Cruze Diesel, obviously automatic, 70 - 75 mph, fairly hilly terrain, 42 mpg on the two lane roads and usually closer to 50 mpg on the four lane roads. The slowing down, then passing and speeding back up really seems to hurt highway fuel economy.
2014 Eco manual - 15k miles. Just drove from Michigan to Georgia going 75-80mph almost the entire way and AC 100% of the time, through mountains and all. We got just under 42mpg and we did some hooning around far past the speed limit lol.
This car gets such great mileage on the hwy it's stupid haha.
A long highway trip at 70mph usually nets me 45-47mpg depending on how hilly the terrain is.
2014 Eco 6MT, 6.5K, I get around 46 mpg average. All I do is highway miles. If I drive around town for any reason I have a bicycle or a beater Ford for that.
Speeds vary from 55 to 65 - fairly flat terrain.
I always use cruise control, and use the accel/decel to change speeds. I usually drop it a few mph when going up hills and pick the speed up on the back side.
I rarely use A/C because my drive is usually in evenings.
I use 91 oct E10 mostly, sometime non-oxy on rare occasions