Need for Speed: Underground Cheats

havyamystikal - Unlock Mystikal car (Toyota Celica)
gotcharobzombie - Unlock Rob Zombie car (Nissan 350Z)
needmylostprophets - Unlock Lost Prophets car (Nismo Nissan Sentra)
119focus - Unlock car
893neon - Unlock car
899eclipse - Unlock car
371impreza - Unlock car
222lancer - Unlock car
922sentra - Unlock car
667tiburon - Unlock car
334mygolf - Unlock car
77peugeot - Unlock car
777rx7 - Unlock car
350350z - Unlock car
111skyline - Unlock car
221miata - Unlock car
2000s2000 - Unlock car
889civic - Unlock car
228supra - Unlock car
240240sx - Unlock car
342integra - Unlock car
239celica - Unlock car
973rsx777 - Unlock car
givemenismo - Unlock car
allmylvloneparts - Unlock all level 1 performance parts
allmylvl2parts - Unlock all level 2 performance parts
seemylvl1parts - Unlock all level 1 visual parts
seemylvl2parts - Unlock all level 2 visual parts
slidingwithstyle - Unlock drifting physics

Easy style points
After you unlock the oval drift track, go into "Quick Race" and choose that track. Then, race around it using the handbrake to powerslide into the corners. Depending on how good you are, you will unlock rewards every time you fill your meter, which does not take too long.

Go to quick race mode and choose any circuit. Set it to five laps with maximum cars on. Then, just get near misses in a row to get a large amount of points. Once your reputation goes up you can make 20,000 points in one go around.

Press [Nitrous] at the start of a race to purge your nitrous for 150 style points.

Unlock the Toyota Celica in split screen/quick race mode and successfully complete the first tournament in underground mode. Go to "Customize Ride" at the main menu and select the Toyota Celica. Select the "Performance" option and equip your new engine, tires and drivetrain. It does not matter what brand package you choose for them. Return to the menu where you choose from "Visual", "Performance", etc. Choose "Visual", then equip your vehicle with parts from all of these options (though putting decals, painting, and placing vinyl on the vehicle is not necessary). Do not use any default parts. If your vehicle does not have a two star reputation rating or more, then you may have forgotten an option. Note: In the body section, the last option may be locked; it is not necessary for this trick. Return to the main menu and select "Quick Race", then "Drift Race". Select your Celica. Select the square track (should already be highlighted), and set the difficulty to medium and lap number to 10. You should be able to easily get "Great Drifts", and if you are good enough, you can get "Superb Drift" and "Colossal Drift" ratings occasionally. You will get a lot of style points for doing these drifts. This is an easy way to get style points early in the game. Also try to do drifts around corners in the bonus zone areas rather then doing drifts throughout the track.

Go to quick race, then select "Drift" and use the little square track. Keep doing this to win vinyls, cars like Eddie's Skyline, the Mystikal car, and more.

Once you have unlocked the orange Acura Type R in Underground mode, use it in regular quick race and win. Doing this will multiply your style points by five because this Acura has five reputation stars. Your style points gauge will fill up quicker, allowing you to unlock other things faster.

Easy drift points
Simply stay behind a car and watch the points rack up.

In drift mode, constantly press [Space] for single hits very fast and turn left and right very quickly. This will give you constant drift points even when you are not in a turn on the track.

Turn off the stability control by going into options and selecting "Car". This will make the car drift easier.

As you progress through the levels, the score required to win the drift competitions get higher, especially when you have upgraded your car's handling. Before you enter the drift competitions, go into "Customize Car" and "Setup". For example, go to the engine upgrade section and refit stock tires to your chosen wheels. This will make drifting much easier. As you approach a bend with a bit of speed, back off the throttle, turn into it, and return to full throttle. With practice you can earn 50,000 style points on the figure of eight style track. Note: Do not forget to refit the better tires before entering a street race.

Shortcuts
Look for alternate routes on your in-game map while driving. These can get you ahead of an opponent easily og shave off seconds on your timer. They will look like another road on the map, but sometimes are narrower. Most of the time these shortcuts will be hard to see or take, and can be extremely risky. At the beginning of the races that take place in front of the prison Samantha told you to race to for at reward, when the race starts, crash in the gate of the prison: It is an underground shortcut. Note: This only works after the race in which Samantha tells you to race to the prison in time for a reward.

Use rims that normally will not fit
Certain cars can only fit so big of a rim. For example, the Miata can only fit 17s, but if you get a car like Skyline put 20s on it and trade it in for the Miata. The Miata will now have the 20s that the Skyline had in it. Do not try to install any other rims on your new car because rimms will go back to the maximum sized allowed.

1998 Nissan Skyline GRT34
Select underground mode and complete at least the first 80 missions. A recommended car to use is the Acura RSX. You will then challenge Samantha. Defeat her under the medium difficulty setting and win the next drag race to unlock the 1998 Nissan Skyline GTR34.

Eddie's Nissan Skyline
To unlock Eddie's car in the end, keep winning style points. Note: It is faster to win them in drift. When your style meter maxes out, a message stating that you have won Eddie's Nissan Skyline will appear.

Shoot smoke from nitrous
To make nitrous shoot out smoke, put your car in neutral, or at the beginning of the race press [Nitrous].