|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 possesses a level of endurance greater than that of the other Nine Titans, allowing for the inheritor to partake in long missions without the need for rest. Its absorption resistance allows it to maintain its Titan form for long periods of time and wear armaments like battle armor, mobile machine gun platforms, and cargo packs for a variety of tactics including the clearing of trenches, and long-term operations into enemy territory. On the downside, the Cart Titan has lower defenses than the other Nine Titans and is more likely to be taken down by a severe blow.
The Cart Titan stands out as unusual among the Nine Titans for its quadrupedal form, which may be the source of its "Cart Titan" name.
The Cart Titan also possesses 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.
Pieck's Cart Titan first appears within the land of the Walls 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 fellow Warriors 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, and 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 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.
Climbing 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, and 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 Battle of 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.
- 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.