I am not yet an Integra owner, but I believe the 44 MPG number could be achieved on a long trip because I've almost matched that in my V6 Accord on a 150 mile trip.
I wouldn't normally do this, but I was tasked to take an elderly couple on a 150 mile trip (75 miles each way, so elevation and wind speed were not much of a factor) and figured that (rather than getting yelled at for driving too fast like I normally do) I'd see what MPG the Accord was capable of. I had gotten 35 MPG on a prior, shorter trip with this couple on board. This time, I was going for 40 MPG.
1. I drove the 2015 Accord with Econ mode on
2. the trip was 95+% highway (Garden State Parkway, NJ, close to sea level)
3. I never went above 62 MPH (100 km/h), Avg speed on the highway was 60 MPH
4. When I needed to come to a stop, I avoided using the brakes until I needed to, foot was off the gas way before any red lights, and I did get a few.
5. The tires I had, were the ones that came on the car, GoodYear Assurance Fuel Max - (terrible tires for everything except getting good MPG)
6. When I had to accelerate to highway speeds from a stop, I did so at a rate that would result in 0 - 60 in 2 to 3 minutes, whenever possible (safe)
7. The car had roughly 25,000 miles on the odometer during this trip
8. Outside temp was 55-58 degrees, cloudy, very light winds, AC was off, windows were closed.
This resulted in 41.1 MPG (car computer calculated), in a 3.5L V6 (VCM equipped, which means it was running on 3 cylinders most of the trip) Accord Sedan with 6 speed automatic transmission.
Driving like this is unrealistic, but it shows that it can be done. I would bet that had I kept speeds around 50 MPH, I would have seen 45 MPG.
