Computer / Gas mileage question ~

Hi Everyone,
I was reading a post about what happens when you disconnect the battery from our Tahoes (mine is a 2001 with the 5.3L) - someone said that the computer has to "relearn" the fuel/air mixtures and not to attempt going thru emissions for a few days after doing so. (They said you would fail emissions if you did)

My quesiton: If I disconnect/reconnect my battery and then go on a road trip where my mph would average 75 - would I get better gas mileage than if I did nothing with my computer as it has been programed by my driving around town - averaging 28 mph or so. Seems like the computer would factor in the start stop attempts, as well as off the line performance - given that it is all calibrated for 1, 2, 3 shifts, etc... and give me worse performance for around town driving. Thus my real question -

Would I achieve better mpg if the computer was relearning fuel curves at a lower cruising RPM, (1500 to 1800) -higher speed (75) right out of the gate (flat surface for 300 miles, with minimal stops and starts). Any ideas and or thoughts?

Has this been discussed before?

Thanks,

Chris