Todd,
I have a 2001 SE,1.8l with 19K miles / 6 speed and often wondered why my Corolla 1.8l gets 35 mpg around town on regular gas, when my Miata, on a good tank, struggles to get 24 mpg. I coast up to red lights, shift at low RPMs, keep my tires inflated, and drive around 60mph. I tried using TORQUE (sorry if I not to mention names of apps in posts) and found something interesting. I set a point x/y graph to display gas flow as compared to RPMs. I watched each gear and performed the test on a flat part of the PA Turnpike. The points merged in 6th gear at 5,700 rpms or about 58 mph. That told me that the car was achieving it's maximum speed / fuel flow efficiency at 58-60 mph. That's fine, but for everyday, around-town driving, but I wanted a better solution. All this was done on 87 fuel.
I put in new plugs, increased the tire pressure from 24 psi to 32 psi and advancing the spark from 10 to 14 and it helped enormously, and no pinging! The car was running too rich and encountering too much rolling resistance. I went from 16 mpg to 31 mpg with just those changes.
Good luck