Jeep has built several different 4x4 systems because not every driver needs the same kind of traction. Someone commuting through Burlington in January has very different priorities from a driver crawling over rocks on a remote trail. That distinction matters when shopping for a Jeep vehicle. Terms such as Quadra-Trac, Selec-Trac, Command-Trac and Rock-Trac can sound like variations of the same idea, but they offer different levels of automatic operation, low-range gearing