It is the last Saturday of the month at Classic BMW. Corner of Spring Creek and North Dallas Tollway. Last month the schedule was from sunup - noon so I am assuming it is the same. I will confirm with my neighbor though. It is a free event but they are accepting donations for Alzheimer's Association, Dallas Chapter in return for a cup of java.
http://www.classicbmw.com/index.php?id=240
http://www.flickr.com/photos/39082328@N08/