Sounds like maybe a fuel problem. I'm not sure how the V8s work with that auto start but maybe try going from off to ignition (but not start) a few times to activate the fuel pump a couple of times before cranking.

__________________
1988 325is (purchased new) sold
2004 X5 3.0 2005 X3 2.5
2008 X5 3.0 (new to me)