Timmy wishes for a super car wash that rejuvenates everything that goes through it in order to repair for Dad's Striker Z sports car. It works, but when dinosaur fossils and cavemen go through it, Dimmsdale is in Prehistoric chaos. And when Cosmo and Wanda go through it, they turn into rebellious teens, causing Poof to disappear since they never married or had him. But, Timmy manages to convince them to become normal again, and they save him from being eaten by a dinosaur and turn everything else normal.
One heavenly Saturday morning, Timmy wakes up from his refreshing sleep. He sees that unlike him, his godparents had to stay up all night caring for their baby Poof. With visible gray circles around her eyes, an exhausted Wanda tells Timmy that they are not as young as they used to be. Timmy tells Cosmo and Wanda that Saturday makes everything better, only to have his dad "mishear" him, thinking he said that he wanted to wash the car. Bringing his son outside, Timmy's dad tells him to polish the Striker-Z de-raccoon it by 5 o'clock. Timmy refuses to, but his dad insists on doing so otherwise, he would take his skateboard and video games. Without another thought, Timmy gives up his toys since he had already beaten the video games and his skateboard was old. Using reverse psychology, Timmy's dad then remarks that Timmy was too young to wash the car anyways and that only smart adults could do so, making Timmy want to wash and de-raccoon the car to prove to his dad that he's old enough to do so.
After getting attacked by the raccoon infestation in the Striker-Z, Timmy tries to wash the car, but the bumper quickly rusts and falls apart. Wanda suggests that Timmy should wish for a car wash that not only washes the car, but makes it brand new, and Timmy does so immediately. With the magical car wash set up, he moves the Striker-Z through it and operates a machine to wash, disinfect, and remove the raccoons from the car, all with the push of several buttons. As the once-old car emerges from the car wash, it is sparkling clean and looks like it did forty years ago. Excited that they could become young again, Cosmo and Wanda decide to go through the magical car wash, but when they come out, they become teenagers, and since they were teenagers, Poof is gone since the couple never got married.
Prancing along the sidewalk while carrying his wife, Timmy's dad sees the beauty of the Striker-Z and announces that he has never loved anything more than his car in his life, filling his wife with jealousy. To calm her down, Timmy tells her that she should destroy the car to get dad's mind off it. She takes out an axe and sets off to destroy the car, thanking Timmy for his idea.
Meanwhile, Timmy tells his godparents to get in the car wash to they can age again or else he'll take away their skateboards and music. Cosmo and Wanda gave him all of their stuff, simply stating that they needed new things anyway. Being the rebellious teens they now were, they refused to listen to Timmy and simply went off to pursue their own interests.
On the streets, an old man driving a truckload of dinosaur bones and prehistoric cavemen notices that there is a car wash. He decides that he should try it out. After the truck exited the wash, the man feels young again, but the dinosaurs and caveman come to life.
Meanwhile, at Lover's Leap, Mr. Turner puts the new piston ring on the Striker-Z, making it shed a tear of joy. He tells her that there is no need for her to cry. Somewhere out of the trees and into the sun, Timmy's mom shoots a missile at the car only to miss and get smashed by a big rock.
Back at Timmy's house, Chet Ubetcha reports that old people are lining up at Timmy's Youth Car Wash to feel young again. Curious, he soon decides to try out the magic car wash himself, but after he exits, he has turned into a teenager and has lost his perfect deep voice. Elsewhere, Timmy grabs a rope of streamers, uses it to form a lasso, and tames the dinosaur with it, commanding it to go to the mall to find Cosmo and Wanda since teenagers hung out at the mall.
In the mall, everyone screams and runs at the sight of Timmy riding the dinosaur. He decides that the only way to find his teen godparents was to look for cool places that teens with attitudes like to hang out. At the skate shop, Cosmo is showing the other boys awesome magical tricks with his skateboard, while Wanda is at the nail salon, showing the girls her fabulous nails and texting them. The dinosaur picks both of them up and drops them off back at the car wash. No matter what Timmy said, Cosmo and Wanda would not listen to him. Remembering what his dad did to get him to wash the car, Timmy realizes that reverse psychology is the only thing that beats teen rebellion. He tells them that he doesn't want them to be a couple after all and that they are just of immature kids that should never change into adults. Wanda back-talks Timmy by saying that he can't tell them what to do, and Cosmo and Wanda make themselves grownups again. Timmy then wishes that the dinosaurs and car wash were gone. Now that Cosmo and Wanda are adults again, Poof reappears.
Meanwhile, Timmy's mom cries miserably as she fails to destroy the Striker-Z. Before wishing away the cavemen, Timmy decides to get them to destroy the car so that his dad would go back to his mom. As Dad slips a wedding ring around the car's antenna, the cavemen pop out from behind a tree and smash the car to bits, much to Dad's shock. Timmy tells his dad that he should return to his mom, and he wishes for a huge diamond ring his dad could give her. As Timmy's dad goes back to the house to win his wife's heart back, his wife falls in love with the ring instead, leaving him heartbroken. At the end of the episode, Dad recruits the cavemen and goes to attack the ring.