Yeah, it's maddening as hell that we spent something like $80 million on a new rental car center as part of $300 million in renovations for the old terminal, completed in 2012 and largely driven by the city hosting the 2013 Super Bowl.
The rental car shuttle already takes a shortcut, using the official vehicle Bainbridge exit instead of the public exit to Loyola. No new road is possible, since you'd have to cross runways.