As an update to what I was saying the other day. This is in the concept stages, but would have the capability to reach 12% light speed in 4, if implemented and it functions properly.
http://www.youtube.com/watch?v=RfsKxnPK6ls&feature=player_embedded
http://www.icarusinterstellar.org/index.php
http://dvice.com/archives/2011/01/project-daedalu.php
