[comptiger5000]

Exactly. It's not a terribly efficient engine (but the 4.0 I6 is no better, just has the advantage of less displacement), and it's in an inefficient vehicle. That's why my focus is on engine mods first, aeromods later. I figure I can gain 2-3 mpg on the highway just from improving engine efficiency a bit.

In my drive cycle, the 4.0 in Mom's Jeep (year newer, 2nd generation, but same weight, similar CDa) gets about 0.5 mpg better around town, and about 1 mpg better highway. At that point, I figured why not get the V8, especially considering the I6 tranny is a bit undersized, and tends to fail if not maintained perfectly.