I found an odd trick for this. Sometimes outside of missions you see police officers wandering about, noticeable by a red shield icon on the radar (these start to show up pretty early in the storyline). They are pretty easy targets as they have little health, are very little threat to you and they don't attack you on sight (at least if you have good karma, don't know about if you are evil yet). Use your
ability to lift up a car (you get this pretty early in the storyline as well) and take your time to get a good throw in. If you did it right you should get a message "Special Delivery +5XP" on the left of your screen. If they just get incapacitated then you can heal them with
+
and throw the car at them again and it seems to count again as I got the trophy hitting the same group of cops a few times.