That Aspen is a sweet rig from what I picked up on
The efficiency difference between 4 cylinder mode on the Tahoe and mine was surprisingly close in my estimation. In the situation where its pulling a moderate hill at indicated 22 mpg mine would be difficult to maintain 26. Take into account that half of the V8 would be more than 30 percent bigger than my 2 liter engine and it seems to do very well. I'd bet yours isn't doing bad either.