Ian didn't want the door to be open, but only because these things were so much easier in private. Not to mention it was much darker in the car than it was outside. His strength was greatly diminished as it was. Still, he was a large man and she was small, so he was winning the battle.
As she stretched her head to look longingly at the false hope for escape, Ian seized the opportunity and sunk the sharpness of his fangs into the pretty expanse of flesh. He made no attempts to cover the pain of penetration and even let his teeth drag down to cause more anguish. He was careful to heal the tears quickly though, because he wasn't about to kill the woman. That would be far more trouble than it was worth.
The moment her blood started to dribble hot into his mouth, he had a more difficult time concentrating on making sure he didn't take too much.