That really sucks you can't open it up!! Take it to a local track
The link will help you understand the sport mode a little better. Most of us drive it in sport all the time, give it a try and you will notice a difference in the way the car acts
http://www.lexusf.com/forums/showthread.php?t=463&highlight=sport
http://www.lexusf.com/forums/showthread.php?t=463&highlight=sport