For the last month or two, ever since the weather turned cooler, I have been having problems getting my 2008 X5 3.0si to start in the mornings. The battery is new and cranks perfectly but the engine just won't turn over. Sometimes it takes 6 or 7 tries, with a full minute of cranking, before it starts. I have taken it to the dealer twice but they can find no problems. In warmer weather, or in the afternoon, it usually starts on the first or second try, which is perhaps why they can find nothing wrong. But for years, this X5 started perfectly, first try, every time. The car is currently at the dealer and will stay for another week in the hope they can find the problem. Any ideas?

Thanks!