This is easily the longest trophy in the DLC. For this you will have to unlock every mod for every DLC car and then takedown someone with the reward license plate. You do not need to have the pro mods, just the standard ones will do.
Firstly, all 5 cars must be unlocked:
Automatically Available: Pagani Zonda R
6 Events: Bugatti Veyron Grand Sport Vitesse
12 Events: Lamborghini Aventador J
18 Events: McLaren F1 LM
24 Events: Hennessey Venom GT Spyder
Each requirement for the mods are the same on all the five cars, this can take a while because one of the requirements is to drive 200 miles.
Off Road: Jump 1500 yards while reinforced Chassis is equipped (need to drive 200 miles before this can be done)
Track: Drive 25 miles
Re-inflated: Drive 50 miles
Burn: Automatically Available
Powershot: Drive 100 miles
Lightweight: Get 60 near misses with Short Gears equipped, (there is a good exploit, see the Road Map for more details)
Reinforced: Drive 200 miles
Aero: Drive 5 miles
Impact Protection: Get 10 takedowns with powershot equipped (only one that cannot be done on your own)
Long Gears: Drift 5,00 whilst track tires are equipped
Short Gears: Drive 10 miles
After this has been completed for all 5 cars (check progress by clicking and then Driver Details, Multiplayer Progress - Ultimate Pack Milestones) select the Ultimate Fan license plate, (change license plate by going to , Driver Details, License Plate). After you have selected the number plate go to an online public game or a private game with a friend and take one person down, the trophy will then pop.
For the requirements all but one of them can be done in a private match on your own. Only "Impact Protection: Get 10 takedowns with powershot equipped" has to be done with at least one other person.