Did some more digging and spent an hour or so trying to work with the files but the add-on vehicles DO NOT WORK. They will all be impossible to drive and flip over constantly, even while following the directions provided with this pack. The vehicles + handling meta files and the carvariations are totally messed up.
Followed instructions and all my SUVs in this pack are flipping. I made sure to replace handling.meta, vehicles.meta, and carvariations.ymt, but still the SUVs are flipping non-stop. Sad part is I can't edit the handling meta because I can't trace back what to edit because the vehicles names (like police52, police51, etc.) are not present in any of the files I mentioned above.