I am concitering putting a 4bt in something but I want to squeze every bit of mpg and proformance I can out of it firts of all stock what can I expect for fuel ecomaney and if I tweak the pump what kind of numbers I know alot of it depends on what I put it in auto or stick and rear gearing just tring to get some numbers.
My approach was to go ahead and get a P30 w/ a 4BT to "live with" the thing for a while before doing the swap. (Plus, need to let the wallet recover / find all the parts for the job.)
On a recent mostly highway trip with my P30 I managed 12MPG. Take that as a "worst case" scenario, as the thing weighs in just shy of 7K LB and has the frontal area of a bus. Also, that's at 75MPH, wide open, turning 3200RPM. Not the most economical operating parameters.
Put the 4BT in something with less weight, better aerodynamics, correct gearing, and not driving like I do, and I'd suspect that 25+ isn't out of the question.