Cheat mode:
Download the cheat enabler from HERE.
Use Juiced_cheatcodes_enabler.exe file.

After start the game, select the "Cheat" option at the menu. 
Enter one of the following codes:

Effect - Code 
All arcade mode cars and some developer tracks  - PINT 
Extra money - CASH 
Everyone respects you - RESP  
All cars - CARS 
Full crew - CREW 
Character test mode - CHAR  
Win all races - WIN. 
Activate all codes - ALL.  

All Prototype parts:
Get 1500 respect points from all CPU characters. 

Completion bonuses:
Get a 100% completion in career mode to unlock prototype mods for all cars in 
career mode and the Extreme Nitrous Series in Arcade Mode. 

Arcade bonuses:
Complete the all the series in Arcade Mode, except the Extreme Nitrous Series, to 
unlock the Bronze, Silver, and Gold Prototype Challenge Series.

Get Easy money:
Earn 600 respect from any CPU character. Then, call any character on your 
mobile phone. Race for pink slips with one of your less powerful cars. After you 
get there, sell it for extra money. Make sure you have more than one car in case 
you lose the race.

Host your own race, then pick sprint. Use your own speedway as the track. 
Select "Watch Race" so that you can bet. T.K. and Biggi will always race against 
each other. Bet on the car with the higher horsepower. You will win about 98% of 
the time.