The "close the car door" movement happens AS you release, not before or after.
Your draw length is determined by the length of your bones once they are lined up. You don't arbitrarily choose that, it is a RESULT of the lining up of the bones. IF you find different draw lengths happening, you are not getting the bones lined up correctly or consistently.
So, As you draw and line up the bones, your hand will come back a certain and repeatable distance, THEN you set your facial references (many call this your anchor point, it really isn't) the bones lined up are. You use BT to maintain the bone alignment then set your string hand on your facial references, WHILE maintaining back tension. THEN, you "close the car door" and the release HAPPENS!
Arne