This is made much easier if you are able to play a private match with a friend/boosting partner.
You can change the settings in a private match as host, by going to the cog icon on the map's image in the lobby, in there you can turn on the setting so that all vehicles are already repaired.
You don't need to find the keys for the car or anything, just meet up with Jason at a car and drive into him 13 times then switch over roles.
I would suggest Crystal Lake Small or Higgins Haven Small for this