Do not quote me because I have not been paying a great deal of attention. I seem to remember this issue on a 997 board, and someone said with the new 2005 cars this feature can be turned on with the PIWIS. This was not the case with 996/986. When I get a chance I'll ask Peter if this is true.
Edit. This is what I read.
http://forums.rennlist.com/rennforums/showthread.php?t=190919&highlight=DRL