I have seen at least 10 of these around where I live (SC). I have identified them by their Hybrid Graphics. Do all of the Hybrid Tahoe/Yukon come with the Hybrid graphics?

FWIW, we own a 07 Denali XL (6.2L - 6-spd auto, no engine management). We see 17-18 on the highway and 14-16 with mixed 40/60 driving. It doesn't take much (i.e. jackrabbit starts or >75mph) to drastically influence FE. Tom's 17-23 MPG sounds real good.