Yeah, that's a good idea. Hopefully I'll get the seats back in before I get the driveshaft, and I can do some more careful testing: I drive a pretty regular route to work, so it should be easy to calculate. When I first bought it, I did the math every week, but the numbers were a little too depressing to think about. I think I'm getting about 14 now: like you, I don't think the change will be dramatic when I hook up the front 'shaft. We shall see!

I try not to let it.

 

My XJ is mostly bone stock minus the heavy duty front bumper and winch, with p235 all terrains, and gets 15.5mpg on a good day. That's with a slight exhaust leak too. I doubt I'd see a difference removing the shaft. Mine's actually out now, I could test if I throw a seat in there and get it inspected...damn PA...lol

 

You will find NO difference removing the shaft. That's why Chrysler discontinued use of the CAD system. You're driving something that has the aerodynamics of a rolling brick.