Should not be much fuel savings with 3.0 vs 4.4, at least on paper but 4.4 will typically include more options. I find it hard to believe they can even ask for $31k for an '06 3.0. I bought an '05 4.8 a year ago with the CPO warranty for about that, granted it was not a BMW dealer and it had 48k mi. Good luck and welcome!

Scott