Simpsons: Hit and Run Cheats

Go to the squidport and jump into the ocean using the Horn jump code, you can land on the water and do plentiful flips and spins.

1st LEVEL - Rocket Car outside (close to) Mr.Burn's Mansion.
2nd LEVEL - Monorail - The First Car of the Broken Monorail System.
3rd LEVEL - Boat - on the big cruise liner inside the green box.
4th LEVEL - 4 WHEELER - On the left of one of the trailers in the
trailer park.

5th LEVEL - At  the stadium jump from the fountain up to
the Monster Truck.
6th LEVEL - DONT KNOW I HAVE YET TO FIND IT.
7th LEVEL - NEXT TO THE BIG ACCIDENT ATOP THE KRUSTY BURGER IS A RC
CAR

Go to the options menu. Now hold L + R then hit Y, Y, Y, Y.

Pause the game an and hold:
L R
and press:
b a b y

Set the system date to December 25th to see various things in the game change to a Christmas theme.

On homers level where u race smithers push carl into the entrance of the power plant then talk to him you will be in the tunnel and will be able to beat smithers to burns house even in the slowest cars.

When you buy different costumes, in each level the character you select will react differently when you allow him or her to remain idle. For example, choosing Bartman will have Bart jump up and fly around for a few seconds.

In the options menu hold L1+R1 and enter the following:

Triangle, Triangle, Square, Square - Blow up vehicles in one hit
Square, Square, Square, Square - Faster cars
Triangle, Triangle, Triangle, Triangle - Fastest cars
Triangle, X, Triangle, X - Infinite car health
Square, Square, Square, Triangle - Press horn to do a huge leap in your car
Circle, Circle, Circle, X - More camera angles
Circle, X, Circle, Triangle - Grid mode
X, Circle, X, Circle - All reward Cars
X, Square, Square, Triangle - Credits
Triangle, Triangle, Circle, Square - Speedometer display
Circle, Circle, Triangle, Square - Red Brick Car
Triangle, Circle, Triangle, Circle - Tripping mode