Just a curiosity question: Do you (or others here) have some real world fuel injected 440 MPG numbers to share with the OP?
It might be helpful to him...

As for that 5.2 in question, my stock 2001 Ram 4X4 with a 5.2 gets right at 12 MPG. That's fuel injected with an OBD II computer. I've heard others say that theirs get better than that, but mine doesn't, and I don't beat on it.