Now that it's a bit cooler at night, my 2006 530xiT is taking longer to start in the morning. With my foot on the brake and the key on start, it's taking 15 to 20 seconds before the starter motor engages.

Any thoughts?

 

Unfortunately I can't be of much help but to recommend you take it
to the dealer. Hopefully it's still under warranty.

 

Sounds like a dying starter motor. Should be very easy to check by the dealer.