The Freightliner FLD that served as Thomas Gabriel's mode of transportation, was a truck that hauled a trailer as his database for his hackers that committed all the events that occurred in Washington, D.C.
Cyber-terrorists Thomas Gabriel, Mai Linh, and Trey, among others, were in the trailer hauled to a Freightliner truck tracking down hackers all over the United States, corrupting their computers, and executing them via explosions (including Clay Wheeler). The truck and trailer are shown to be hiding in a warehouse, serving as Gabriel's hideout.
When news came from Rand and Del that Matt Farrell, a targeted hacker survived, Gabriel becomes furious and tells all his hackers, including Trey and Casper, to locate his whereabouts. When it is revealed he is in Washington, D.C. (with John McClane), Gabriel commands all his comrades to switch all traffic lights green from the trailer. Once that has been done, all cars crash and collide in the streets.
Afterwards, Gabriel's hackers send a video message to the United States in a compilation of the nation's 32nd to 43rd presidents. Then, in the FBI police car, Mai Linh takes over the dispatch transmitters from the trailer, disguising herself as a dispatcher. But Farrell recognizes her voice and warns McClane, who tells her to "cut the chit chat".
Back in the trailer, Gabriel tells Trey to unblock all paths to the tunnel that McClane and Farrell escaped into, but is hesitant to do so. Gabriel, who does it himself, tells him not to hesitate again.
After Mai decides to fly to Eastern Power Hub with two henchmen, Gabriel tells a henchman to get Trey to come see him. When he leaves, all hackers in the trailer are killed. Disposing their bodies, Gabriel and his remaining henchmen leave in the tractor-trailer and proceed to Woodlawn.
After capturing Lucy McClane and Farrell, Gabriel, Emerson, and Trey enter the van while Robinson drives the truck. McClane follows by and shoots Robinson, killing him. When Gabriel sees the truck speeding up and approaching the van, he notices McClane and attempts to outrun him.
He calls a jet pilot, flying a F-35 Lightning, to take out the truck, not telling him it is being driven by McClane. The jet fires missiles and shoots the truck and trailer, all the while McClane tries avoiding being hit. When the jet takes out a portion of the freeway bridge, the truck is falling back and McClane has no choice but to exit it in order to survive. The truck is soon destroyed along with the jet, but the pilot manages to eject the jet before it crashed and McClane jumps off the jet and into the collapsed highway ramp to survive.