The relationships of Mater.
Mater came across McQueen for the first time, when the latter was put in the impound by Sheriff. When McQueen thought that Mater did not know his name, Mater made a guess that he is named Mater as well, but soon learned his actual name when McQueen introduced himself to Luigi and Guido while first fixing the town's main road. When Sheriff had put him in charge of watching McQueen for the night while he is fixing the town's main road, Mater decided to take him out to go tractor tipping, believing that he would love it as well. Afterwards, Mater began playfully taunting McQueen when finding out that McQueen loves Sally, and it also led to Mater revealing to McQueen that he can drive backwards so well. McQueen then explained to Mater that if he wins a racing competition called the Piston Cup and gets sponsored by Dinoco, he will no longer have to encounter rusty old cars, but immediately added that he actually meant other ones so to not insult Mater, who then said that it is okay, as he forgave him immediately, as well as that, he has been wanting to ride in a helicopter his whole life, after McQueen mentioned that the team has a couple of them, to which he agreed to let Mater ride in one.
Along with the rest of the townsfolk, Mater felt very saddened when they thought McQueen had left after completing the road, but soon became glad when he realized that McQueen actually did not go. However, McQueen was soon transported away from the town by the press, leaving Mater very saddened once again by the fact that he did not manage to say goodbye to him. On the day of the final Piston Cup race at the Los Angeles International Speedway, Mater and most of the townsfolk came to be part of McQueen's team, where Mater said goodbye despite the fact that he would be seeing McQueen throughout the race, along with seeing McQueen use his trick of driving backwards after being rammed by Chick. He was soon left wondering what McQueen was up to on the final lap after he stopped before reaching the finish line but later cheered on for him when seeing that he was trying to push the King to the finish line so that he could finish his final race. Mater was soon given a ride in one of Dinoco's helicopters, after McQueen asked Tex, and has since become best friends with McQueen.
However, there are times when Mater and McQueen are unable to see each other, due to McQueen's racing career, and especially when Mater was not invited to any of his previous races. After McQueen got back from winning the Piston Cup for a fourth time, Mater was feeling overexcited to see him again, as well as having planned a whole lot of stuff for them to do together in the summer. However, on the first day, McQueen decided to take a break by spending time with Sally at the Wheel Well, but without Mater, who felt disappointed. Aiming to still spend time with McQueen, Mater pretended to be a waiter at the Wheel Well, although he had trouble knowing what was McQueen's usual drink. When he saw Francesco Bernoulli talking about being faster than McQueen on a talk show, Mater felt angered and telephoned the show to say that no one should insult his best friend. McQueen soon came into the restaurant and took Mater's place to talk to the show, agreeing to take part in the World Grand Prix. With advice from Sally, McQueen invited Mater to be part of his pit crew for the competition.
However, Mater was not used to all of the different stuff outside Radiator Springs, which concerned McQueen. During the World Grand Prix race in Tokyo, Mater helped McQueen to get into the lead, but when he got distracted by Holley Shiftwell talking to him through his headset and away from the circuit, Mater's discussion with her made McQueen lose the race. Mater did not realize this until McQueen angrily informed him that it was all because of him, adding that he did not want Mater's help again. Feeling deeply saddened and ashamed by seeing his best friend angry at him, Mater decided to go back home to Radiator Springs so to make sure he is not responsible for someone else beating McQueen in his future races.
While helping Finn and Holley on their mission to hear who was the mastermind of a group of lemons, Mater heard McQueen saying to the press on TV that he had been missing him since leaving Tokyo, making Mater feel the same. Upon hearing that the lemons were planning to kill McQueen for his decision to use allinol in the final race, Mater felt shocked, and rushed to try and warn him, but was captured by the lemons before McQueen could get to him.
While tied up inside Big Bentley in London, Mater felt very upset as Grem and Acer prepared to kill McQueen with the lemons' electromagnetic pulse generator. However, McQueen did not explode, leaving the lemons perplexed and to go to a back-up plan, where they told Mater that they had put a bomb in McQueen's pit. After they left, Mater was able to get free and rushed to save his best friend. However, he soon realized, after being informed by Finn and Holley, that the bomb was actually on him, and when McQueen noticed him in the pits, Mater drove away, trying to keep his best friend out of danger. However, McQueen went after him, unaware of what was really happening. Not wanting to get themselves killed, Mater told him to keep away, but McQueen did not understand and went closer and closer to Mater. Just as his hook got grabbed by McQueen's front wheel, Mater began noticing that the lemons were going to make the bomb explode at any second, and gave a voice command to his computer to use a pair of rocket boosters, making the two friends go out of range. Still not wanting both of them hurt, Mater ordered McQueen to let go, but McQueen refused, not wanting to lose him again. As soon as Holley and Finn arrived, McQueen was able to finally realize about the bomb.
As Mater soon figured out who was the one that activated the bomb, McQueen said that he had been wrong the whole time, after learning some advice from Uncle Topolino, and that Mater should just behave like he did in Radiator Springs, and other people should change instead. After the bomb was turned off by Axlerod, Mater also cheered when McQueen allowed him to come to all of his races starting from that moment. Back in Radiator Springs, after being allowed by Finn and Holley to keep his rockets, Mater joined McQueen in the Radiator Springs Grand Prix, happy to be spending time with him again.
Mater came across Holley Shiftwell while he was in Tokyo with McQueen's team. She greeted him, and he was beginning to have deep feelings for her immediately. When Holley told him that they would be rendezvousing the next day, he was wondering what a rendezvous was. With Luigi answering that it is similar to a date, Mater immediately got into thinking that the rendezvous was a date. The next day, while acting as McQueen's crew chief for the first World Grand Prix race, Holley hacked through his headset, telling him to get out of the pits, to which he eventually did, believing that he was being given directions to her location for a date. While strolling through the city, he came across a flower shop and asked Holley if she would like some flowers. Holley's answer was to carry on, and Mater followed every piece of information until he misheard Holley saying to concentrate, thinking that she was saying to drive toward a ruckus, which happened to be Finn and a couple of lemons fighting. After the fight, Mater was told by Holley that he could not continue and that they would keep in contact, although he thought that he missed the date.
The next day, when Finn took him onto Siddeley, Mater was very excited to see Holley again, still claiming that she was his date, leaving her confused and shocked. While examining an engine photo, Mater realized that Holley and Finn are secret agents, and attempted to woo Holley while they were still wondering who had the engine shown in the photo. When they were traveling to Porto Corsa on Stephenson, Mater noticed how Holley was able to get some filming of the lemons driving through the town, believing that she is not only the prettiest car that he ever met but the smartest too. When Holley was trying to fix his dents while trying to make a disguise of Ivan fit on him for the lemons' meeting in Porto Corsa, Mater explained to her that he does not fix his dents because he does not want to forget them, having got some of them while spending time with McQueen.
While Mater was in disguise at the casino with the lemons, Holley warned him through the communicator that he had to be careful about his speech, because that others around him are able to hear him. This made Mater start to wonder if Holley wanted him to not talk to her before Alexander Hugo noticed that he was acting strange. Soon, Mater was told by Holley to evacuate, because Finn had got captured by the lemons before she too got captured. Mater was starting to drive out of the lemons' meeting, but Alex noticed him, saying the lemons were having a great party.
However, Mater soon got captured after blowing his cover and was tied to the gears of Big Bentley in London, where he also noticed Finn and Holley tied up as well. After Finn mentioned him being a good spy, Mater admitted to both him and Holley that he is not a spy, making them both shocked. When Grem and Acer left the tower, Mater was able to get free and was wanting to help Holley and Finn, but they told him that he had to go and save his best friend McQueen. While Mater was trying to save McQueen after being informed about that the lemons had planted a bomb on him, Holley came and told him to stop, but he declined, not wanting to get her hurt as well.
After Mater was declared a hero for making Axlerod turn off the bomb, he and Holley became a couple, as revealed when Holley and Finn came to visit him and his friends in Radiator Springs. The two spies soon had to go for their next mission, while Mater decided to stay at home, but Holley informed him that she will come back and that he still owes her their first date.
In Cars 3, it is revealed that Mater and Holley's relationship is still going very strong and at the end of Cars 3, Mater distracts Sterling by mentioning that he has wedding flaps, hinting that he's someday getting married to Holley Shiftwell. He still loves her unconditionally and she still loves him unconditionally.
- “Spy or not, you're still the smartest, most honest chap we've ever met.”
- ―Finn complementing Mater after their mission[src]
In Cars 2, Mater first encounters Finn McMissile in Tokyo when the former witness the later demonstrating his karate skills to dispatch some Lemons. At the airport, McMissile finds Mater and pulls him aside for the two to introduce each other, then work together to escape Grem and Acer who had been following them.
When Finn McMissile stops by in Radiator Springs to visit Mater sometime after the mission to uncover the true conspiracy behind the World Grand Prix is concluded, he complements Mater for being the smartest and most honest chap.
- “How did the tow truck figure it out?”
- ―Axlerod, after he is exposed[src]
At the beginning of Cars 2, Miles Axlerod felt amazed when Mater called into the Mel Dorado Show, so to talk to Francesco about McQueen. He felt like he had to thank Mater for doing so, since it made McQueen agree to compete in the World Grand Prix. He did thank Mater while in Tokyo, only for Mater to say he is the one who should thank. Immediately, Axlerod leaked oil, blamed Mater so that no one could find out that he was actually not an electric car.
In London, Mater proved to the British Royal Family and police that Axlerod had been leader of the lemons, along with that he was the one who leaked oil. Axlerod tried not to reveal his cover, telling everyone that Mater was out of his mind, and ordering him to keep away when Mater prevented him from escaping. However, Axlerod's cover was revealed when he deactivated the bomb that the Lemons had put on Mater, which had only been one second from detonating. Afterwards, Axlerod was left wondering how Mater was able to figure out the whole thing.