[Jackpine]

There could be a few reasons:

1. The Hypertech's tunes are better than the Gryphon's canned tunes. (There, I said it!)
2. The Hypertech was biased more toward economy and the Gryphon is biased more toward performance.
3. Your driving habits have changed?
4. You are relying on the Average Economy display in the Gryphon instead of doing a "hand calculation".
5. The Tire Size on your vehicle was incorrect after programming with at least one of these devices. (Possibly both.)

Of all the reasons I've shown above, Nbr 5, incorrect Tire Size (TS) is my favorite. I just did a quick lookup at the Hypertech Manual for their Max Energy Econ model, and I notice you have to pay extra to be able to correct the speedometer. Did you get this feature?

If not, is your TS and Gear Ratio (GR) stock? If not, you WILL have to correct these - in either the Hypertech or in the Gryphon. Now, it gets tricky:

A. If you have non-stock tires or gears and did not correct for these with the Hypertech, any MPG you calculated would be wrong.
B. IF you "opened" the "Custom Options Menu" in the Gryphon and DID NOT enter correct values for TS and GR, your fuel economy would be wrong (probably low).
C. IF you have non-stock tires or gears and did not adjust for these with the Gryphon, your fuel economy would be wrong (probably low).

And, even if you do have stock tires and gears and opened the Custom Options Menu - If you DID NOT "set" your TS and GR, you are probably going to see low values for economy.

So, think about all this, and let me know what's going on.

- Jack