On 2007 and earlier cars they are the "flash to pass" lights.
On 2008 and newer they are just corner illumination lights for turning and backing up.
I wish they were still flash to pass. I had a 2005 530i and was used to the flash-to-pass lights. But on the 2008+ they use the HID high beams for the flashing, and once when I first got the 2008 I was trying to signal an elderly couple to cross the road in a parking lot at night by flashing the lights. Well, I didn't realize the HIDs would flash and when I hit them with the HIDs and you would have though I hit them with a photon torpedo or something... they lit up like a spotlight and the poor old guy raised his arms to block the light even.