Since Lori is the only one of the Loud children to have a driver's license, she's the only one (aside from their parents) who can drive her siblings to wherever they need/want to go, provided they do her chores and other favors for her in return. Lincoln's tired of doing Lori favors just to get her to give him a ride, and is surprised that Leni has to do it as well, especially considering that she's legally old enough to drive. Leni explains to her brother that she doesn't have an official driver's license yet and that she's failed the road test twelve times before, and nobody's willing to teach her how to drive anymore. Seeing an opportunity, Lincoln decides to help Leni get ready for her next road test, figuring that if Leni had her license, she wouldn't force him and the rest of their sisters to do favors for her in exchange for rides like Lori does.
Lincoln tries to train Leni with a video game that utilizes with a wireless wheel controller. Leni keeps losing at first, but Lincoln gives her motivation by saying that they're going to the mall. This helps Leni win the game, and she feels confident to take her test again, but she is brought home by the police for driving recklessly like in the game.
On Lincoln's next attempt, the rest of the sisters (minus Lori) decide to join in and help their brother get Leni ready for her road test--as it turns out, Leni and Lincoln's eight other sisters are just as tired of doing stuff for Lori in exchange for rides as Lincoln is. Lincoln and the sisters fashion a makeshift car to help Leni learn good driving habits, but Leni doesn't understand the technical names for things, like the wheel and turn signal (calling them the "spinny thingy" and "blinky blink," respectively). Lincoln realizes that he has to talk down to her level to get her to understand. By using simple terms and fashion lingo, Leni's able to drive the fake car, and then the lawnmower, flawlessly, and again feels ready to ace her next road test. But Lori, not wanting her siblings to weasel out of doing stuff for her, wants to make sure that Leni fails her test. Later that night, Lori slips on a pair of headphones onto Leni's ears and plays a tape that teaches bad driving habits.
The next day, after Leni leaves to take her test, Lincoln refuses to do anymore of Lori's laundry for a ride since Leni will give him (and the rest of their sisters) rides without forcing them to do favors for her, but Lori reiterates by saying that Leni won't pass because she assured it, accidentally revealing her treachery. When a suspicious Lincoln threatens to shrink her favorite Bobby-sweater, Lori confesses to her sabotage--ultimately, she claims that she did it because she's worried that Lincoln and the rest of their sisters won't need her for anything if Leni ends up getting her driver's license. Lincoln calls Lori out on her selfishness, pointing out that because of what she did, Leni could get herself and others seriously hurt (or possibly even worse). Realizing the severity of what she did, Lori (now greatly worried about Leni's safety) drives herself and Lincoln to the local DMV to stop/help Leni.
After arriving there, Leni comes out of the building-- as it turns out, Leni's perfectly fine, but she did fail her driver's test again, this time due to the bad instructions from Lori. After some insistence from Lincoln, Lori confesses to Leni about what she did, and to make it up to her, she agrees to help Leni train for her next test, which proves to be far easier said than done.