Here is the full list of all 24 Street Racer Underground trophies - there are 6 bronze, 10 silver, 7 gold and 1 platinum.
Earn all other trophies
Buy your first car
Buy 5 cars
Buy all available cars
Buy your first set of rims
Buy 5 rims
Buy 10 rims
Customize the body of a car
Buy all body customizations for a car
Customize the accessories of a car
Buy all accessory customizations for a car
Customize the windows of a car
Buy all window customizations for a car
Customize the rims of a car
Buy all rim customizations for a car
Buy all the paints for a car's parts
Upgrade all atributes of a car to the maximum level
Reach the X4 nitro multiplier
Reach a score of 5000 on endless mode
Reach a score of 1000 on endless mode
Finish first in the bronze race
Finish first in the silver race
Finish first in the gold race
Finish first in the platinum race