O6 Ranger 4.0 v6 got 27 mpg. Fluke?
 

Vehicle- 2006 ford Ranger STX 4.0 v6 2 wheel drive clutch
Definition of vehicle- extended cab 4 door. Factory bumper like a body kit for a tuner vehicle. Stock has the Mazda b-series bed but I have the old fashioned 90-00s splash bed with no tailgate. The truck has a DJM 4/5 suspension body drop with Superduty coil isolated that are modified to raise the nose about 1.25". K&n airnfilter. Ford's latest ATF (used in the M5OD-R1HD manual trans). Moble1 0w30 oil. Stock 3.55 rear limited slip. Intake hose mod-cover. Bed liner (black plastic drop in). No bumper. Stock tires in the front, continental contitracs. Rears are Firestones (forget what name but pretty aggressive truck treads) stock 30 30 pressures.
Load- cleaning supplies, some tools, sub box and subs, a tire in the bed (no rim).
Scenario - So I filled up with premium, then went to Hawthorne nj via rt206, 80, 287, and rt 208. Filled up with premium again (again the second pop on the nozzle). Then did the reverse of 208 to 206. Got to the station at 80 miles and filled up to the 3rd click on the pump handle at less than 3 gallons.
The whole way i kept between 55 and 67 mph give or take a couple MPH. I would go neutral on a grade drop of >2.3* (measured via pioneer Avic-d3). and had my heater fan on 3 or 4 depending on my choice. And the selector to floor since it's the only one that doesn't turn on the A/C. Sometimes windows cracked a little (less than 2" drop. with rain guards) I would cruise with the fullest lane and feel the resistance behind a truck or car and go with it. Inside turns up hill and outside to inside down hill trying to keep inertia.

So does it sound like a calculatory fluke or legitimate high score? Previous my best was 23.5 mpg, but this is a huge difference!

And I changed the tune to performance from economy. Increased power. Right after I filled up with the full tank of amazing milage.

Unfortunately, I'm gonna have to say "calculatory fluke". I don't think there was enough miles and gallons to be extremely accurate, but a good commute none the less.

Use those strategies and keep entering fuel logs and you will be able to better tell if that performance will be sustainable.

I just don't think my truck is capable of 27 mpg yet. Although the measuring top off went a little more than the previous, I thought it would be closer since more was put in.
Today I am at about 120 on a 1/4 tank. (I had been doing a bit of idling and harder acceleration due to the traffic flow and cops being out. Plus short trips as well.
I am going to temporarily use 27 as highway milage though until I can get a consistent number.

Check your fuel pump, I got an increase in mpg just before it stopped.

The results are the same. Great FE before 1/4 tank used. Once at the 3/4 mark the consumption flattens out.

A few months later I traveled to MN from NJ and was able to get 27.9 mpg at highway speed calculated tank to tank.

Those are good numbers but they're a bit iffy on such a short fill. Rack up some longer runs and see how she does.

Getting high 20s on a V6 Ranger is pretty good, if you can pull that kind of result over 400 miles in a single tank, that's less likely to be the result of some fluke in the fill or ideal conditions.

New Jersey to Minnesota is not a short run. It's an oil change.

No, I know that. I'm commenting on your (so far) sole log entry which only shows us about 80mi worth of records, and nothing in the three years since.

I know the NJ-MN route (most of it), I used to live in N. VA and made the trip to MN several times. Now I live in TN and have made that trip which is, paradoxically because I live about 550 miles S/SW of my old digs outside DC, about the same distance. Not having to dogleg over the top of W. VA makes a big difference.