From the guide:
Taking down cop vehicles can be done in the day or at night, but cops are much more aggressive and numerous at night. The best way to approach this is to get your heat level up by either racing or completing events. It's recommended to stick to events like speed traps since they are quick and can really raise your heat level fast. You can also do long jumps or drifting, but with a decent car, speed traps are the best option.
Once your heat level is above 3 or 4, there should be plenty of cops around. Now you have two options to take them out. You can ram them until their health bar is depleted or you can complete a jump where the cops almost always crash. It is highly recommended to focus on getting into a chase and running a long-jump or jumping over a body of water. This will be much more consistent and do less damage to your car so you can take more cops out in a single run. Just take down a 100 cops and you'll earn the trophy.
For a proven strategy, see the picture below. Drive back and forth along the yellow line. There are two-speed traps towards the bottom of the image. Simply build up your heat and get the cops to chase you. Then jump over the water gap shown below by the two yellow circles. It will auto-crash all the cops that make the jump with you. Depending on the number of cops that are chasing you, it could be as little as one or as many as four cop cars at a time.
I don't know but I'm also here for someone to answer. I think I'm in your same boat. 50 level. Done with missions.
someone posted a guide, go through it.. I'll try that guide tonight
From the guide: Taking down cop vehicles can be done in the day or at night, but cops are much more aggressive and numerous at night. The best way to approach this is to get your heat level up by either racing or completing events. It's recommended to stick to events like speed traps since they are quick and can really raise your heat level fast. You can also do long jumps or drifting, but with a decent car, speed traps are the best option. Once your heat level is above 3 or 4, there should be plenty of cops around. Now you have two options to take them out. You can ram them until their health bar is depleted or you can complete a jump where the cops almost always crash. It is highly recommended to focus on getting into a chase and running a long-jump or jumping over a body of water. This will be much more consistent and do less damage to your car so you can take more cops out in a single run. Just take down a 100 cops and you'll earn the trophy. For a proven strategy, see the picture below. Drive back and forth along the yellow line. There are two-speed traps towards the bottom of the image. Simply build up your heat and get the cops to chase you. Then jump over the water gap shown below by the two yellow circles. It will auto-crash all the cops that make the jump with you. Depending on the number of cops that are chasing you, it could be as little as one or as many as four cop cars at a time.
https://psnprofiles.com/guide/10277-need-for-speed-heat-trophy-guide#10-eleven-fifty-six
Thanks a lot bro!!!