Hi Don; no modifications. After reasonable breakin period, I changed my oil and am using Mobil 1 synthetic. Ford already has a pretty efficient I-4 engine. I wouldn't know a way to modify it, and it would void the warranty.
You are right, the EPA estimate is 29 mpg highway. That is quite easy to exceed. Some methods I am using include: mostly driving on country roads, hiways, or freeways (very little city use), accelerate slowly and smoothly, seldom ever use the brakes, inflate tires to maximum, tonneau cover, drive at moderate speeds, and very importantly, HAVE A REAL-TIME MPG GAUGE WORKING AS A CONSTANT REMINDER!
More tips include: when parking at, say, Wal-Mart, NEVER drive around looking for a space. Just immediately pull into one, all the way through, so you DON'T have to back up to get out. Also, on long trips take your shoes off. Sensitivity to the gas pedal is key! If you have cruise control, fine, but manually you can out-drive it for mpg. Also, in very cold outside temps, block off most of the radiator with cardboard or something similar. (I have not done this with my Ranger, it's warm enough outside) Also, when shopping for new tires, choose LRR (low rolling resistance) and remember tall & skinny is better, low profile & wide is very bad. Also, slightly better mpg is acheived using straight gasoline (no ethanol). Also, in the morning don't sit and warm up the engine. Just begin driving at a light load & speed. In cold weather, an engine block heater is a great way to save fuel.
There are many other techniques; many of them are considered "extreme" and not practical in normal traffic flows.
Really, just look at our ratrace/society: typically a gal gabbing on the cell phone, driving solo in an SUV, rushes up to a stoplight and slams on the brakes. Amazing......