[Lil' Lavery]

Drive to your heart's content Jay. The problem with having graduating drivers step down is it doesn't really solve anything. In fact, it makes it much harder to create consistent and experienced drivers. It shortens a drivers "lifespan" from a maximum of 4 years, to a maximum of 3 (and therefor their time to practice and learn to drive, even if they aren't on the drive team). The problem with not allowing seniors to drive is what happens a couple years from now:
"I'm a junior driver, and my team doesn't allow seniors to drive, so this is my last year eligible to drive. Should I pass the torch to the sophomore driver so he can gain experience this year and help the future of the team?"

Really though, it comes down to the goals of your team. Does your team want to succeed this year, or is it building and prepping for the future? Are you dabbling in new technology and design idea/philosophy to try and prep for the future? Or are you sticking by the proven and true and making tweaks to try and push you over the top?