Cheat mode

Enter Career mode. Select the "Secret Code" option at the menu. Enter one of the following codes to activate the corresponding cheat function. The message "Congratulations! Your code has been accepted and your reward has been unlocked" will appear to confirm correct code entry. Most codes can only be enabled once. Therefore it is recommended that the auto-save option be disabled before using the codes in the event you wish to revert the game to its original state. Also, using some codes may reset the performance of cars that have previously been improved.
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Master code

Enter UNLOCKALLTHINGS to unlock the map, more cars (2004 Pontiac GTO, Chevrolet Cobalt SS, Dodge Viper SRT10, and another Nissan 240SX), all of the race days, and stage 4 performance parts.
Bailey Caldwell

Xbox 360 This code functions only in the unpatched version of the game.
Money

Enter 1MA9X99 as a code for $2,000.

Enter W2iOLLO1 as a code for $4,000.

Enter L1iS97A1 as a code for $8,000.

Enter CASHMONEY or 1Mi9K7E1 as a code for $10,000.
ffemt2016, ExarK9, Christen Gooding, Chris Thorsby, Ray Cornelius, and others

Wii Enter REGGAME as a code for $10,000.

PlayStation3 Xbox 360 Enter REGGAME as a code for $10,000 and some cars including the Chevrolet Camaro Concept, Ford Mustang GT 500, and Nissan R34 Skyline.
Outlaw6271
Five free repair markers

Enter SAFETYNET as a code.
Christen Gooding, Chris Thorsby, and steven kidder
Coke Zero Volkswagen Golf GTI In Career mode

Enter ZEROZEROZERO as a code.
steven kidder Xturbo
Energizer Lithium Dodge Viper SRT10 in Career mode

Enter WORLDSLONGESTLASTING as a code.
Ed Napiorkowski, Grim Reaper, and Matt James D
Mitsubishi Lancer Evolution in Career mode

Enter MITSUBISHIGOFAR as a code.
steven kidder
Castrol Syntec decal in vinyls

Enter CASTROLSYNTEC as a code. Note: This code will also result in an additional $10,000.
Ed Napiorkowski and SGC32
Energizer lithium decal in vinyls

Enter ENERGIZERLITHIUM as a code.
Ed Napiorkowski and SGC32
K&N decal in vinyls

Enter HORSEPOWER as a code.
Ed Napiorkowski
Relock cars

PlayStation3 Xbox 360 Enter LEIPZIG as a code to lock all cars previously unlocked with the UNLOCKALLTHINGS code.
Geoffrey
Audi TT 3.8 Quattro in Career mode

PlayStation3 Xbox 360 Enter ITSABOUTYOU as a code.
Ed Napiorkowski
Progressive Insurance decal in vinyls

PlayStation2 Wii Enter ITSABOUTYOU as a code.
Bonus Collector's Edition cars

Wii Enter COLLECTORSED as a code in the Collector's Edition to unlock the Acura NSX, Acura Integra, Audi RS4, Lexus IS350, and Pontiac Solstice GXP.
Unlockables
Prequel bonus

Have a saved game file from Need For Speed Carbon to receive $10,000, five small repair markers, and a large repair marker.
Completion bonus

Get a 100% completion and defeat Ryo. You will not have to pay for any repairs or totals of any kind.
Geoffrey
King rewards

Defeat the indicated opponent in Career mode to unlock the corresponding car. Defeat all of the Kings to unlock free repairs for all your cars.

2006 Mustang GT: Drag King (Karol Monroe).
2008 Evo X: Showdown King (Ryo Watanabe).
2008 M3 E92: Grip King (Ray Krieger).
1965 GTO: Speed King (Nate Denver).
1995 RX-7: Drift King (Aki Kimura).

Hints
Recommended cars
Custom cars
Easy money

Enable the "Master code" then go to the car lot. You will find a red Acura Integra available for $0. You can sell it for $7,200 and can repeat this as many times as desired. You can also sell the other cars obtained when that code is enabled.
chris west

Enable the "Master code" then go to the career map and enter any event. Exit the event the first chance you get. After doing this, go into your garage. You will see that four new cars have been added to your collection: a Nissan 240 SX, a modern Pontiac GTO, a Chevy Cobalt SS, and a Dodge Viper SRT 10. You can keep any cars desired, but by selling all four of these newly added cars you can get $90,290 quickly. You can reset the game and repeat the process until you get the desired amount of money.
steven kidder and Marco Muyot

You can use the "Relock cars" code to sell your old cars again. Enable the "Master code" when you start the game and before you do any racing. Participate in a short race in career mode, like a 1/4 mile drag. When done, go to your garage. This will give back the old cars that you won and sold earlier. You can sell them again to get lots of money. You can repeat this as many times as desired, but must shut the game down and restart it each time to do this trick.
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Use the following trick to get $91,500 in just a few minutes.

Enter Career mode. Select the "Secret Code" option at the menu.
Enable the "Master Code".
Go to any Race Day.
Immediately leave the Race Day.
Go to the garage. Notice that you now have four cars unlocked: the Pontiac GTO, Chevrolet Cobalt SS, Dodge Viper SRT10, and Nissan 240SX.
Sell them all. You can get $91,500 in total.
Quit the game.
Start the game again.
Repeat steps 1 through 4.
Those four cars will respawn in your garage.
Sell them all again.

Repeat all the steps as many times as desired to get money quickly in order to buy and upgrade your cars.
deadtimothy666

This trick is best done with auto-save enabled to makes things faster. Go to Career mode and enable the "Master Code". Go to an event day. As soon as you can, leave that event day and go to your garage. You should see that you have a few extra cars. Sell those cars to get about $90,000. Go back out to the main menu. As you do this, the auto save will kick in and save the game. After it is done saving, reset the system. Notice that you no longer have the cars you sold but you will still have the $90,000 you received from selling them. This trick can be used as many times as desired. Also, because you have everything unlocked you can use this trick to get a Lamborghini, a Chevelle, a Skyline, or anything else desired at the very start of the game. The fully enjoy this cheat, play the game as far as the Chicago Showdown.