Full Auto

I would like to add something to previous solutions. This is my method. You only need 2 players in the game. Choose Containment and Class A vehicles, Outlaw is preferred. Choose Assault or Melee. As soon as you spawn for the first time, keep going forward (you do not have to move the control stick during the game). You will find yourself in front of a cliff that leads to the ocean. The other player will spawn behind. None should move the control stick. Once your weapons are ready, both players should drive to the cliff shooting each other. You don't have to kill each other, just fire a couple of rounds. The one on the back shoots the one in the front, and the one in the front throws grenades or mines to the one in the back. You will both dive in the ocean and the game will give a kill to both players (if you shoot somebody and he falls off a cliff, you get the kill). Both players will spawn right back in the same position. So keep moving forward while shooting the other player and keep falling off the cliff. Get to 70,000 or so just to be sure, then go around and finish the race. Both players should get more than 30 points, although you can only get a max of 30 per game (as said by other players. I haven't checked this).

This can be easily boosted with a friend. Select a multiplayer game and search for a game. there are so few people playing online now you will nearly always find your friend first time. Any circuit will do and either race normally for the long way to this, or kill each other 30 or so times then complete the race.

Due to the dwindling number of players actively racing online, this may require a boosting partner.

It appears that Level 1 can be earned just by running a single ranked race on Xbox LIVE. I earned this Achievement despite finishing third in a three-person race, in which I picked up 4 points. If anybody finishes a race with fewer than 4 points earned and still unlocks the Achievement, please feel free to update in the comments section.