I've been trying to modify my driving habits to increase my fuel economy using a Scan Guage. It's not as easy as it would seem.

At first I assumed the MPG gauge would be most useful but when you think about it, it's a function of speed and throttle position so I've started to use the TPS function instead. Seems more useful.
The biggest problem area seems to be Freeway during the commute. I drive in the car pool lane because I work with my wife. I don't think it's a good idea holding up traffic so that put's me at 65-70 with frequent periods of slow and go 30-40. 18 miles each way. Constantly varying TPS. Result with that added to city stop and go, 23.6 mpg.
Weekend trips on Freeway, constant 60 mph with cruise control gets 26.5. Even then with cruise engaged I'm amazed at how muck TPS fluctuates. I've found myself wondering what it would take to modify the CC to maintain throttle position regardless of speed for situations where you're not in traffic. That might get some results.

Generaly, 20 TPS or less seems to be the most economical. Comments?

Better to learn to pay attention to your foot than to fixate on a digital readout. An old-fashioned vacuum gauge is actually better than the ScanGauge because you can monitor it out of the corner of your eye; it's obvious where the needle lies. OTOH the ScanGauge (or similar) demands you see, recognize and interpret a numeric readout when your eyes really should be on the road.

IMO using the cruise control and the "egg on the gas pedal" throttle method will be not only safer but also more effective than watching the ScanGauge.

Can't disagree. I've started monitoring TPS more. I've also cut back on the use of cruise on hilly terrain. Once the 5 speed AT downshifts to maintain speed, you can kiss your MPG goodbye.

I have the Scan Guage mounted atop the steering column and like to adjust the steering wheel where it blocks the view of the speedometer (remember the guy who actually cut of the top of his steering wheel?) so I'm using the Scan Gauge for a speedometer. In traffic I adjust my speed to traffic rather than the speedometer anyway. I check the TPS when I'm accelerating and on occasion to try to maintain a constant throttle. I'm 61 and spent many years averaging over 50,000 miles a year (sales job) and other than being rear ended I've never been in a wreck. That probably means I'm due so I should probably take your advice Dan...