Press [`] and type in:

 hereComesTrouble       Enable cheat mode

 openLevelsGuv          All levels accessible
 cash                   + 10,000 Dollar
 setCar [CARNAME]       Change Your car name to [CARNAME]
 makeai [CARNAME]       Create opponent with [CARNAME]
 invincible             God mode
 ai on/off              AI ON/OFF
 WasteAll               Destroy all cars
 lastlap                Start on final lap
 lastcheckpoint         You only need to clear the last checkpoint
 adventure              A text adventure hidden game
 damage_multiplier #    Increase damage to #
 addPowerup #           Add powerup (#=Name)
 breakCar #   Damage car (#=Name)
 peds on/off   Pedestrians ON/OFF
 enablebuy   Buy all cars if you want

 And you might also try:

 bendCar
 splitCar
 wasted
 almost_wasted
 setlevel
 renderPaths
 vel
 carsuspension
 setCarSlipMutt
 setCarEnginMutt
 incCarCenterX
 incCarCenterY
 incCarCenterZ
 setCarAPO
 endlevel
 enablebuy
 lastlap
 lastcheckpoint
 endMission
 setshitter
 powerups
 peds
 b_render_cars
 b_path_followers
 b_mission_update
 b_drones
 b_nuke
 b_special_volumes
 nextlevel
 difficulty
 revs
 fonttest
 sfxinfo
 campos
 debug
 setCockpit
 SetTestVal1
 SetTestVal
 SetTestVal3
 rendernames
 hardshadows
 RenderLights
 missioncheatah
 net_debug
 obj_detail
 renderPedColData
 b_particles
 b_hud
 b_radar
 b_sound
 b_physics
 b_tex_anim
 b_level_script
 b_replay
 b_task_manager
 b_sky
 b_track
 b_anim_props
 b_water
 test_cars
 b_clampdt
 speedTest
 reloadBridges
 crash
 fp_getnetinfo
 skyfog
 skyfogcolour
 skyfogrange
 trackfog
 trackfogdist
 trackfogoffset
 trackfogcolour
 foginfo
 netLookAhead
 chat
 netSetLag
 throttlemessages
 throttlemsgcount
 throttlebytecount

 ---

 Go to the Assests folder of the game and edit the file options.txt. Search for
 the string USE_TIMER and change the value from 1 to 0. Now the timer is off.

 ---

 To edit the power ups check the file PowerupStrings_Internal.txt in the
 assets folder.

 ---

 Load the carma.pak file from the assets folder with wordpad and scroll till
 ENDDIFFICULTY. Here you will find the attributes for anything you will get money for.
 Change this numbers and remove the line APO_TRADE_OFFENSIVE at the end of this section.