Resurrecting this thread as I believe I have the same issue as the OP and did not want to start a new thread.

It looks like there was no solution to the crank, no start problem, other than troubleshooting and problem went away...

Problem Summary:
The issue I am having appears to be related to the weather. Car has not exhibited any ignition or performance issues up until yesterday when I tried to start the car at 10 degrees F (6:30 AM). The engine failed to start after the starter was cranking for a long time. After a few more attempts, it would finally start and would run smooth the whole drive (25 miles, mostly highway). I drove it again during my lunch break (noonish) and again at 5 PM when I left work to go home, with no starting issues whatsoever.

The next day (today), same issue occurred, but this time I failed to get the engine running. After the excessive cranking, the battery started to lose juice and thus not enough juice to start the engine.

Based off this, I don't believe the issue is related to battery or alternator as there was plenty of juice to be able to start the engine. It only ran out because of several attempts of cranking for 5-10 seconds each time.

Because it is very cold, I decided to get it towed to a mechanic down the street and the car has not been serviced yet. I am hoping I can get some ideas before they call me back.

Here are some possible ideas I have gathered and not sure if I am missing something:

Fuel Delivery (Fuel Pump / Filter): I will ask the technician to check the fuel rail pressure. Although not sure if this makes sense since it ran fine yesterday and if it was truly a faulty pump, then the motor would have shut off during my drive.

Battery / Alternator: Again, don't think this is the issue, but I think the issue is cold weather related and batteries do not like the cold.

Crankshaft Position Sensor: Not really sure, would cold wintry weather cause this part to fail? I don't believe this part has been replaced and at the car's age and mileage I am most likely overdue on this life of this part.

Ignition Switch In my opinion, this is probably the culprit. Bad contacts maybe?

In summary, all I really know at this point is that when its really really cold, it will not start. I am willing to bet when they service the car later today it will probably start since it warmed up a little bit. This issue occurred yesterday when the temperatures dipped to single digits the previous night. Prior to that, it was in the 20's and I have never had this issue before.

My car is a 2005 X5 3.0i with 196k

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2005 BMW X5 3.0i
2013 BMW M3 Competition