Each of the new cars has 8 events that you need to win/gold for this trophy. 6 events are "traditional" races, ambushes etc, while the remaining 2 consist of Smash and Grab and Drift events.
Smash and Grab has you smashing targets in a specific area. If you check your minimap, you will see small and big yellow dots. These mark crashgates (small ones, 50 points each) and billboards (big ones, 250 points each). You shouldn't have any trouble on these as gold limits are very reasonable. If you struggle however, try to see if you could line up several gates fast by looking for patterns on your minimap. I recommend you do these first before the drift event as they will reward you drift tires for a gold score. After you get them get 5, 50 yard+ drifts to unlock the pro ones. After you have drift tires pro equipped, start the new drift event. These might take you a few tries but aren't terribly hard. Remember that the higher your speed and higher your drift angle is, the more score you get. Try to get some combos in also, this is done by maintaining drifts through several gates without touching them.