Originating from Western contractor's penchants in Iraq and Afghanistan for driving big, sometimes armored, SUVs during the course of their operations, Xe being the former Blackwater Security company and one of the largest in operations within the theater.
Many contractors drive these vehicles in highly agressive manners and have illusions of being superheros while behind the wheel due to the unregulated power these contractors often wield. Thus much like Batman and his Batmobile Xe contractors have their Xemobiles.
Contractoer 1: "Dude what vehicle are we using for the resupply run?"
Contractor 2: "Xemobile #24" pointing to the 3rd black Suburban in line.
Dude 1: "Wow nice Expedition! Whose is it?"
Dude 2: "That's my Xemobile man! I got it when I got a riase last month."