It seems like no one is updated their gameconfig.xml files to the newest 1180.1 version yet(or whatever the number is as of 10/1/2017) So here is the guidelines for what you need to edit in the gameconfig.xml file yourself and keep it up to date without having to rely on someone else to do it for you. It is super easy and I recomend notepad++ but even notepad with basic windows will do the job just fine, here are the values you must edit after every update to keep your addon car mods working and the current values I use with the latest update(these change every update so you have to re-edit them every time)

<PoolName>Vehicles</PoolName>
<PoolSize value="400"/>

<PoolName>VehicleStreamRequest</PoolName>
<PoolSize value="160"/>

<PoolName>VehicleStreamRender</PoolName>
<PoolSize value="200"/>

<PoolName>VehicleStruct</PoolName>
<PoolSize value="300"/>

<PoolName>HandlingData</PoolName>
<PoolSize value="1050"/>

<PedsForVehicles_Base value="175"/>
<PedsForVehicles value="175"/>

<VehicleMemoryMultiplier value="600"/>

<VehicleUpperLimit_Base value="140"/>
<VehicleUpperLimit value="230"/>

<VehicleParkedUpperLimit_Base value="140"/>
<VehicleParkedUpperLimit value="200"/>

<MaxVehicleModelInfos value="420"/>

<MaxExtraVehicleModelInfos value="350"/>

<PoolName>FragmentStore</PoolName>
<PoolSize value="13200"/>

These values change with every update so just add 100 to whatever the current value is in your gameconfig.xml file in your mods/update/update.rpf/common/data folder and you are golden...unsure of total amount of addon car mods is with these values but I have it working with 12 addons right now and no infinite loading screens and no crashing, cheers peeps!