Changes for 678.1 game version (these are only values I modified versus original gameconfig.xml). Works with Pinnacle of V and about 30ish addon/15-20 replacement vehicles and all game DLCs. YMMV.
<PoolName>FragmentStore</PoolName>
<PoolSize value="9550"/>
<PoolName>Vehicles</PoolName>
<PoolSize value="900"/>
<PoolName>VehicleStreamRequest</PoolName>
<PoolSize value="145"/>
<PoolName>VehicleStreamRender</PoolName>
<PoolSize value="135"/>
<PoolName>VehicleStruct</PoolName>
<PoolSize value="300"/>
<PoolName>HandlingData</PoolName>
<PoolSize value="800"/>
<PedsForVehicles_Base value="130"/>
<PedsForVehicles value="150"/>
<VehicleAmbientDensityMultiplier_Base value="130"/>
<VehicleAmbientDensityMultiplier value="150"/>
<VehicleMemoryMultiplier value="800"/>
<VehicleParkedDensityMultiplier_Base value="100"/>
<VehicleParkedDensityMultiplier value="150"/>
<VehicleUpperLimit_Base value="100"/>
<VehicleUpperLimit value="260"/>
<MaxVehicleModelInfos value="900"/>
<MaxExtraVehicleModelInfos value="300"/>
<MaxExtraWeaponModelInfos value="200"/>