Mudflap was an Autobot and the "brother of Skids. Mudflap was noisy and hyperactive, not unlike his brother. However, despite their annoying perosnlaitys, they deduced they worked best as a team, which is also the worst thing for the Autobots, who would have had to put up with two bickering hyperactive siblings when not fighting the threat of the Decepticons.
The twins were first into action for N.E.S.T.s mission to Shanghai, slowly trundling through the city streets in their ice-cream truck mode and taunting Decepticons in the area to show themselves. Two Decepticons soon did: Demolishor and Sideways. At NEST's orders, the twins went after the smaller foe and, working with Arcee, managed to herd him into an alleyway. However, their slow, ungainly choice of alternate mode left them unable to keep up with Sideways. While Arcee leapt through a building to pursue the Decepticon, the twins tried to go around the building to catch him. However, the twins inadvertently split apart from one another when they rounded the corner too sharply, thus taking them out of the chase. Mudflap took the blame for the crash, but Skids still berated (and smacked) Mudflap for his failure. Upon arrival to Diego Garcia and NEST headquarters, the twins were given new, individual alternate forms to make sure another incident like that never happened. Mudflap wanted the Chevy Beat as a vehicle form, but after a brief wrestling match with his brother, he was relegated to the form of the Chevrolet Trax.
Later, the twins, along with the other NEST-allied Autobots, were dispatched to look for Sam Witwicky when Decepticons were detected heading towards his college. After Optimus Prime was killed by Megatron, the twins helped the Autobot force fight off the Decepticon leader and Starscream, allowing Sam, Leo Spitz, Mikaela Banes and Bumblebee to make good their escape. Skids and Mudflap met up with Bumblebee and the humans, and together they fled to a remote location. After the twins teased Leo for a while for his panic attack, Sam inquired whether one of them could interpret the Cybertronic symbols with which he had become obsessed. The twins claimed that they couldn't read the ancient Language of the Primes and weren't much into reading, anyway.
.With the help of the Decepticon Wheelie and former Sector Seven agent Seymour Simmons, the group made their way to the Smithsonian, where the humans reactivated the venerable ex-Decepticon Jetfire. He teleported them all to Egypt before telling them the tale of the original Primes, the Star Harvester, which had the potential to destroy all life on Earth, and finally, the Matrix of Leadership, the key to activating the harvester and possibly the only thing that could bring Optimus Prime back to life. When the Matrix could not be found at the ruins of Petra, Mudflap questioned why they where helping Sam, wondering what they had done for the Autobots. Skids pointed out that Sam had killed Megatron, but Mudflap said the point was moot since Megatron was now back. After calling each other "scared" and "ugly" the two began to fight with one another. After damaging the structure and nearly crushing the humans, Bumblebee picked the twins up, bashed them together, and threw them out the door. However, their bickering created a hole in the wall where the Tomb of the Primes lay, and with it, the Matrix.
Making their way back to the Pyramids where NEST waited with Optimus Prime's body, the group came under attack by Starscream. Mudflap, Skids, Leo and Simmons acted as a decoy to lure the Decepticons away from Sam and Mikaela. Unfortunately, they attracted the attention of the Constructicons, who combined into Devastator and attacked by vacuuming up loose objects such as sand, cars, and Mudflap. Hanging on for dear life inside the monster's mouth, he tried to use his "kung-fu grip", but was sucked further inside, losing his shoulder guards in the process. As Skids mourned the loss of his twin, Simmons realized that the safest place to be was directly under the giant. But he had survived being vacuumed up by Devastator, and to escape he had blasted a hole through its head. To buy the humans time to escape, Skids clambered up Devastator's right forepaw to assist Mudflap. Skids threw a cable to Mudflap, who grabbed it and swung off Devastator's head onto his arm. However, once they had landed, Mudflap accidentally shot Skids in the face, knocking them off. At Megatron's command, Devastator continued onto the Great Pyramid of Giza. Mudflap and Skids were not seen in Egypt after this.
Mudflap and Skids were at the end of an Autobot convoy as the team rolled into the hangar of NEST's Washington, D.C. base.
Mudflap was later parked next to Sideswipe when Sam arrived at NEST HQ for the first time. Mudflap and Skids did not join the Mission aboard the Xantium to retrive Sentinel Prime, but remained at the NEST base. Later, Mudflap and Skids were still inside the NEST base when Sentinel Prime turned traitor and killed Ironhide. He then charged inside the base to take back the Pillars, but not before blasting Skids with his Cosmic Rust gun, killing him. Furious over the death of his twin, Mudflap lunged at Sentinel, who killed Mudflap with a single shot to the head. Sentinel then stole back the Pillars.