i have a similar problem with my 4.4 v8, it starts perfect first thing in a morning but if its left after a run and come back to it an hour or so later it finds it a bit hard to start some times
i am having the same problem, starts straight away when it's cold but just drains the battery turning over when hot. My RR is going in to "my man" tomorrow and having a new 4th injector (sensor) he is so confident that it will fix it he said if it doesn't he'll take it out and not charge me a penny!!
Hi
I had the same problem with my which gradually worsened ... until the turbo failed (Garret turbo). Apparently its common in the BMW X5 as well. Good luck!