After Lisa returns home with Bart, Marge discovers that her son's mind has been completely fragmented. Distraught, Marge runs around town trying to find anyone who can help her cause. Eventually, she manages to pinpoint Bart's problem: the aliens' Buzz Cola. Despite his claim of an extraterrestrial source, Marge consults Apu to see if he knows where the soda is coming from. He is unable to answer, and in a fit of rage, Marge takes her already active annihilation of the soda into full throttle, destroying Cola Trucks as a result.
Level 4 is set at Evergreen Terrace and reuses the map from Level 1 but with a few modifications: Instead of taking place in the day, the level takes place at dusk/evening just before nighttime. The gates to Mr. Burns' mansion have been opened allowing the player to gain access to the mansion. One of the gates of the grey house facing/in front of the mansion has been opened and Buzz Cola glass appears on top of the mansion's fence. The chess board behind the mansion has also become accessible via car now unlike in Level 1 whereas the area can only be accessed by-foot (with the exception of cheats/glitches). Behind the Simpsons' house, the window to Bart's bedroom has been opened, and the player can now enter Bart's bedroom, which includes a Character Costumes icon allowing the player to change clothes. Lastly, the tomacco field by the power plant has been imprinted with an image of Bart's head, causing most of the plants to disappear.
Level 4 shares the same normal music with Level 1.
- For A Few Donuts More
- Redneck Roundup
- Ketchup Logic
- Return of the Nearly-Dead
- Wolves Stole My Pills
- The Cola Wars
- From Outer Space
- Bonus: Beached Love
- Canyonero (Starting vehicle)
- Tractor (Purchase from Willie for 400 coins)
- Kremlin (Bonus Mission)
- Clown Car (Street Race prize)
- Curator (Purchase from Gil for 300 coins)
- Krusty's Limo (Purchase from Gil for 350 coins)
Main Article: Wasp Cameras#Level 4
Main Article: Gags#Level 4
- The TV inside the Simpsons' House.
- The swings in the Simpsons' backyard.
- Grill in the Simpsons' backyard.
- Talking tiki in the Simpsons' backyard.
- Krusty table lamp in Bart's room (backyard window).
- Door of the bomb shelter in Flanders' backyard.
- Radioactive gas tank in the power plant parking lot.
- The lever in Homer's workstation at the power plant.
- Fire extinguisher inside the school.
- Fire alarm inside the school.
- Frostillicus in the Kwik-E-Mart.
- Silent alarm behind Apu in the Kwik-E-Mart.
- ATM in the Kwik-E-Mart.
- Larry the Looter arcade at the Kwik-E-Mart.
- Squishee machine at the Kwik-E-Mart.
- Main article: Level 4 Collector Cards
- This is the only level of a couple of things:
- This is the only level in the game where a player isn't required to buy a car from a particular character in order to initiate or complete a mission.
- This level, along with Level 3, are the only levels where Homer has no role in the main story. He only interacts with the player in the two levels as an optional driver for both the Family Sedan and the 70's Sports Car. However, he does appear in the Simpsons' house eating slices of cheese in the kitchen, and is heard when Ned Flanders approaches the window.
- This is the only level where Hans Moleman has a story role.
- If the player smashes the headlights of their vehicle, they will still be working regardless.