We've talked about
:
Lean tune the local guys do to pick up 1-2mpg.
Energy saver a/s tires with lighter wheels (~150 pounds lighter for a set with correct load cap as well o.o)
Meziere EWP (100% reduc of mech water pump).
UDP (25% reduc on pump, compressor, and generator).
Smooth out body (racks, rails, etc... only need to tow).
3.08 or 2.73 gears
If the new tahoes can squeak out 22-24 mpg around 65(?) mph from (w EPAS and aero with the 6 speed) the factory it seems like this could as well with appropriate load, rolling resistance, and drag reduction which seems pretty straight forward.
This video talks about the v4 mode with the 6.2 Escalade and how it gets 23-26 mpg at 65 mph with 87 and 93.