|The Cart Titan, with its unusually high endurance, is well suited to long missions. This allows us to equip it with armaments, expanding the variety of tactics at our disposal.|
|— A Marleyan analysis of Pieck's Cart Titan|
The Cart Titan possessed a level of endurance greater than that of the other members of the Nine Titans, allowing for the inheritor to partake in long missions without the need for rest. Its absorption resistance allowed it to maintain its Titan form for long periods of time, making it an ideal candidate for a variety of tactics, including the clearing of trenches, and long-term operations into enemy territory. Likewise, Pieck claims that the Cart Titan's power allowed her to perform hundreds of consecutive transformations before she started to feel fatigued. On the downside, the Cart Titan had much lower defenses than the other Nine Titans and was more likely to be taken down by a critical or severe blow. Another major disadvantage was that inheritors of the Cart Titan did not have the same regenerative speed as the other Titan inheritors, requiring a longer period of time to heal wounds received in combat.
The Cart Titan stood out as unusual among the Nine Titans for its quadrupedal form, which may have been the source of its "Cart Titan" name. As a side-effect to inheriting the Cart Titan and staying in its form for extended periods of time, the inheritor was liable to forget how to walk normally and would instead crawl like the Cart Titan. Pieck was often seen crawling similarly to the Cart Titan when in the presence of few people, and also used crutches when getting around.
In addition to its combat abilities, the Cart Titan was often used to carry supplies or troops during times of conflict. Examples of this include during the course of the Great Titan War as well as the Battle of Shiganshina and the Marley Mid-East War thousands of years later. In addition, the Cart Titan was also used as a mobile gunnery platform, being able to wear harnesses that could hold various weapons; this included several machine gun turrets and much larger weapons such as an anti-Titan artillery cannon.
The Cart Titan also possessed great speed, similar to the Jaw Titan, which was used during the Battle of Shiganshina to retrieve a defeated Zeke Yeager and Reiner Braun while also catching Levi and Hange, two of the Walls' most talented soldiers, off guard.
The Cart Titan, like all the Nine Titans, was brought into the world after the death of Ymir Fritz. In the 1,700 years following her death, the Cart Titan was held in the possession of one or several of the warring Eldian houses subservient to the Founding Titan. After these seventeen centuries when Karl Fritz, the 145th King of the Fritz family, abandoned the conflicts of Eldia and relocated to Paradis Island, the Cart Titan was taken by the nation of Marley during the Great Titan War.
Around the year 843, Pieck was chosen to inherit the power of the Cart Titan. She would later make use of her Titan form during a war between Marley and an enemy nation, using her Cart Titan to drop off Bertolt Hoover at a site for transformation.
Five years into the mission to reclaim the Founding Titan, Pieck journeys to Paradis Island with Zeke and a contingent of Marleyan soldiers, using her Cart Titan to carry supplies for them. She is present as Zeke and the soldiers transform the inhabitants of a small village into Titans.
Pieck's Cart Titan later appears during the battle of Shiganshina District. During the night before the battle, Pieck keeps watch for Survey Corps movement in the desolate regions of Wall Maria south of Trost District. Upon seeing the advancing soldiers, Pieck returns to the ruins of Shiganshina and informs Zeke, Reiner, and Bertolt of their approach.
Later that day, Pieck's Cart Titan remains at the side of Zeke's Beast Titan, serving as a cargo mule of sorts for the Warriors' various supplies in addition to fetching boulders for Zeke to throw at their enemies. Bertolt is kept hidden in a barrel atop the Cart Titan's back as a plan B against the Survey Corps; upon Reiner's defeat at the hands of the Survey Corps' Thunder Spears, Bertolt is removed from the Cart Titan and thrown by the Beast Titan into the city. Shortly afterward, the Survey Corps chooses to engage in a suicidal charge against the Beast Titan in order to buy time for Captain Levi to move in for a counterattack. Pieck ventures away from the scene as Zeke decimates the Survey Corps, only to be quickly defeated by Levi who catches him unawares. Before Zeke can be captured by Levi, Pieck's Cart Titan comes to Zeke's rescue and carries his dismembered human form away.
Sitting atop the Cart Titan's back, Zeke guides Pieck into Shiganshina to rescue Reiner and Bertolt. They find Bertolt incapacitated and captured by Eren Yeager but after seeing Levi atop the Wall, they leave him for dead. Searching elsewhere in the district, the Cart Titan rescues Reiner from capture before climbing atop Wall Maria where the Warriors are safe. With the battle over, the three survivors return to Marley.
Four years later, Pieck is present at the battle of Fort Slava during the climax of the Marley Mid-East War, but the use of her Cart Titan is prohibited under orders from Commander Magath, who could not risk losing a Titan to the Mid-East Allied Forces' anti-Titan artillery. However, once cadet Gabi Braun destroys the armored train carrying the artillery using explosives, Pieck is able to join the battle alongside Porco Galliard's Jaw Titan. Equipped with fully functional battle armor with four machine gun turrets manned by Marleyan soldiers, the "Panzer Unit," on the Cart Titan's back, Pieck enters the trenches of the Allies and destroys their bunkers, eliminating the outer defenses of Fort Slava.
During the Raid on Liberio, Pieck has her Panzer Unit equip her Titan with the heavy machine-gun armament. Though it takes time, she believes it would be perfect against the anti-personnel vertical maneuvering equipment. When she arrives at the battlefield, she and the Panzer Unit take the Survey Corps by surprise with an artillery barrage from the roof of a building, saving Porco and killing several of the nearby soldiers. She stays perched on the roof and joins the rest of the Titans of Marley in a showdown against the Survey Corps. However, both the Cart Titan and the Panzer Unit are eventually ripped apart by Thunder Spears and the Titan plummets into the streets below. Jean Kirstein attempts to finish it off while Falco tries in vain to stop him; however, a burst of steam coming out of the Cart Titan hits Jean, and the Thunder Spear he shot misses its target. Pieck emerges unconscious and injured from the Titan's body, and is rescued and taken away by Falco and Gabi.
About one month after the Raid on Liberio, Pieck makes use of her Titan to sneak into the Walls, eventually infiltrating the Yeagerists once inside. In Shiganshina District, Pieck comes into contact with Eren Yeager, luring him into an ambush by the Jaw Titan. Though the initial sneak attack fails, Pieck is freed from her shackle which had been binding her to Gabi, allowing her to transform into the Cart Titan.
After Gabi climbs into the Cart Titan's mouth, it runs away to meet with General Magath and his soldiers. The Cart Titan fills in Magath on the situation's details, surmising that the Founding Titan's powers will be activated once Zeke and Eren come into contact. Once Pieck finishes outfitting her Titan with an anti-Titan artillery cannon, Magath climbs inside, before the Cart Titan and the soldiers manning its cannon scale Wall Maria. As the Jaw and Armored Titan struggle against Eren's Titan, the Cart Titan fires a round into its head, compromising Eren's mobile abilities. After reloading, they shoot Eren through the head again, though the arrival of the Beast Titan ruins the Warriors' opportunity to finish him off.
After destroying the Marleyan airships, Zeke attacks the Cart Titan by throwing rubble from the Wall. Avoiding engaging Zeke in a firefight, the Cart Titan takes cover by clinging to the side of the Wall, but is soon forced to flee across it due to a group of pursuing Yeagerists. As the Cart's pursuers are distracted maneuvering into a pincer, Pieck uses the opportunity to exit her Titan and feign defeat. While Zeke, and the pursuers are confused, General Magath shoots the Beast Titan through the nape, sending it plummeting down the Wall.
Soon afterwards, Pieck returns to Titan form and reequips the anti-Titan artillery cannon. They fire another round into Eren's Titan's head, and readjust to aim at the Beast, who had survived the earlier attack. The pursuing Yeagerists run interference, forcing Pieck to fend them off. After killing all but one of them, the Cart Titan fires on Zeke again, seemingly finishing him off. Before they can fire at Eren, a soldier knocks off the artillery with a Thunder Spear, and another soldier then kills the last members of the crew defending her. Pieck proclaims it is over, before going to attack her assailants, who begin grappling towards her.
Before the Cart Titan can engage its two assailants, Wall Maria begins to crack underfoot, signifying the beginning of the rumbling.
The Cart Titan and Magath retreat from Shiganshina's remains and observe Marley's airships leaving the island. While discussing the situation, the two are interrupted by an approaching soldier. Pieck prepares to attack, but stops when the soldier insists that they and their partner are harmless. After finding their goals align, Pieck and Magath agree to join forces with the two.
In order to gather companions, the Cart Titan feigns an attack on the Yeagerist's headquarters, and uses the chaos to abduct Jean Kirstein, Onyankopon, and Yelena. After shaking off any pursuers, Pieck rendezvous with her comrades, and later joins with the other members of the makeshift alliance.
The following day, the Cart Titan is sent to scout Paradis's docks to see if it will be safe for the group to follow Eren. Pieck returns from her mission to reveal that the Yeagerists have occupied the docks in anticipation of retaliation against Eren.
During the ensuing conflict, it is decided to take the flying boat to Odiha. The Cart Titan alongside its passengers then evacuate to the Azumabito's ship. As the Armored and Female Titan are overrun, Falco Grice rushes into the battle transforming into the Jaw Titan. The Titans along with the Survey Corps are able to defeat the Yeagerists but Falco quickly loses control of his Titan and attacks his allies. The Cart Titan's nape is almost crushed with Pieck inside. However, the Cart Titan is able to restrain the Jaw Titan long enough for Magath to remove Falco from his Titan.
- The name of the Panzer Unit, the four-man artillery crew atop Pieck's Cart Titan, is derived from the German word "Panzer," meaning "armor," specifically the armor of a heavy vehicle or tank.
- Hajime Isayama has stated the Cart Titan's Panzer armaments were based on his love for Zoids and that it was not drawn until the day of the manuscript's deadline.