In your 'instal folder'\cars\ you can find one folder for every cars in the game. Edit the files vehicle.ini and in the section vehicle damage definition place 0 (zero - null) for every hit mentioned there.
Your car will not look smashed every time you hit a car or a wall.
Also verify damage.ini to contain 'zonenum=0'
In your instalation folder of the NFSHP2 you can find the CARS and TRACKS folders. In these folders edit the files cars.ini and tracks.ini, and replace the prices of the tracks with 0 (zero). Play the game and the cars and tracks will be unlocked.