Heart, a young girl car, is recently licensed. Just like any other new car, she goes to the auto show to find her new family but because of her small and insignificant appearance, she doesn't get chosen by anyone. Heart-broken, she goes out to the street and runs into Hana, the mechanic, who is all dressed up for a day out.

Heart receives a cute siren as a gift from Hana. Lani, already envious of Heart, becomes even more upset when Heart gets all the attention from everyone. That evening, Heart's siren disappears! The little buses suspect Lani because of her jealousy for Heart.

Rubby's cleaning equipment breaks down while sweeping up the junk that Rogi has collected at one side of the playground. Rogi, responsible for the cause of the incident, is given the task to take over Rubby's job until the equipment is fixed. And Rubby enjoys his first holiday in a long while, with his friends.

Tayo is now familiar with his daily routine and grows annoyed by Hana's concerns. One day, Tayo gets to take care of Bongbong and the other baby cars. He wants to prove to Hana that he is all grown up by carrying out his job flawlessly.

Tayo and the little buses are due to start school tomorrow. Tayo is excited and coincidentally runs into Teach who has just moved to the town to attend the same school the next day. Tayo spends time with Teach and then returns to the garage where he is told that the teachers at school will be very scary.

One day, Frank heads out to extinguish a fire on top of a skyscraper. While Frank is having trouble reaching the fire on the top story, Air appears and puts it out. From that day on Frank continues to train hard but ends up being distressed after failing again to extinguish a fire on a tall building...

The little buses become dejected when they don't have an interesting story to tell at their school presentation on what everyone did over the weekend. The little buses nag Citu to take them somewhere special and Citu, who hasn't been able to spend enough time with them for a while, decides to take them to the zoo for a fun-filled exciting weekend.

Tayo breaks his promise to hang out with Duri. He feels sorry and makes another promise to Duri that he will let him ride with Frank or Pat. But his promises constantly fall through due to unexpected incidents…

One day, Gani coincidentally saves an action star, Reo. He gains fame as a brave bus that saved a superstar and even gets a personal manager for himself. But alternating between his work as a bus and other press schedules constantly tires Gani…

Bongbong tries to ride on Toto's tow hook for fun but they become stuck together as the pintle breaks. Toto, already late for school, has no choice but to take Bongbong along. And constantly gets into trouble because of Bongbong's immature actions. Toto just wishes he was not attached to Bongbong...

Pat is working hard to enforce the traffic rules. As he harshly scolds the little buses and kindergarteners, they become more and more scared of Pat. One day, a feather sticks to Pat's back by accident and he can't control his laughter every time it tickles him...

Speed and Shine always cause trouble together. While at school Shine gets a chance to be complimented along with Lani, Rubby, and Toto. Not only are they praised together but they also share a common color, yellow. They become close very quickly and spend most of their time together like best friends. On the other hand, Shine's best friend, Speed, feels left out when Shine only hangs out with his yellow friends...

Cooku and Champ visit the city for the first time. Although Cooku is unfamiliar with the area, she is too proud to admit it and ends up acting as if she knows everything. The two of them eventually land in an awkward and even dangerous situation.

One rainy day-off, Lani spends the whole day taking a nap and ends up not being able to sleep well that night. The next day, sleepy Lani keeps humiliating herself but cannot sleep again at night. From that day on, Lani's sleepless nights continue.

Heart and Hana come to help Speed who got hurt while fooling around. Speed is attracted to Heart at first sight with her pretty looks and kindness. He makes various plans to become friends with her but things only go wrong.

Tayo and Duri are very impressed by the deeds of superheroes on TV. When they coincidentally help a friend in need and get praised that they are just like superheroes, they get very excited. From the next day, Tayo and Duri dress up as superheroes and go out to offer their help to the townspeople.

The construction vehicles are bored with their daily routine of tiring work. For a short break, they perform some acrobatics. Joey the Magician approaches and compliments them on their moves and asks if they would be interested in joining his circus. The heavy-duty vehicles accept the offer without much thought.

Tayo is upset after being embarrassed because of Hana's clumsiness. Citu tells Tayo how he first met Hana and how she became a mechanic.

Tayo finds a lost puppy. Despite Hana's instructions that he can't raise it at the garage, he cannot let the cute puppy go and decides to keep it secretly. Tayo builds fond memories with his friends and the puppy while keeping it all to themselves.

Rogi is made fun of at school because he always gets the questions wrong and takes the wrong roads to ride on. To restore the others' faith in him, he visits the smart Met and takes special lessons from him. Rogi starts gaining recognition little by little with Met's help.

Poco receives a flower seed as a gift from a girl that he helped. He does not take the tiny seed seriously at first but soon becomes very fond of the growing sprout.

On Christmas eve, Tayo steps out to receive a present from Santa who only gives them to good children. Tayo's intentions are well-meant but he keeps messing up. Meanwhile, Santa's sack of presents gets a hole in it and he ends up dropping them all around the city.

A space pirate, Bully, keeps chasing after Princess Ray but without success. Bully finds Hana and mistakes her for the princess and comes straight to earth. Hana gets captured by Bully's gang and the little buses gear up with the help of Princess Ray and go to the rescue...

The little buses gear up with the help of Princess Ray and go to rescue Hana. Meanwhile, Hana fixes the wounds of Wooly, Bully's son, and discovers his warm-hearted nature. When the little buses arrive at Bully's castle, barely escaping his soldiers to enter it, they fall into Bully's trap. Will they be able to save Hana?