Strange this doesn't work :

<Item> <VehicleModels> <Vehicle>police3</Vehicle> </VehicleModels> <PedModels> <Ped>S_M_Y_Cop_01</Ped> </PedModels> </Item> <Item> <VehicleModels> <Vehicle>nfsgs350</Vehicle> </VehicleModels> <PedModels> <Ped>S_M_Y_Cop_01</Ped> </PedModels> </Item> <Item> <VehicleModels> <Vehicle>nfs458</Vehicle> </VehicleModels> <PedModels> <Ped>S_M_Y_Cop_01</Ped> </PedModels> </Item> ...

But this does :

<Item> <VehicleModels> <Vehicle>police3</Vehicle> <Vehicle>nfsgs350</Vehicle> <Vehicle>nfs458</Vehicle> <Vehicle>nfs718</Vehicle> <Vehicle>nfsf430</Vehicle> <Vehicle>nfsgt500</Vehicle> <Vehicle>nfsrs</Vehicle> <Vehicle>nfszonda</Vehicle> <Vehicle>nfsrevent</Vehicle> <Vehicle>nfsveyron</Vehicle> <Vehicle>nfsccx</Vehicle> <Vehicle>nfsp1</Vehicle> </VehicleModels> <PedModels> <Ped>S_M_Y_Cop_01</Ped> </PedModels> </Item>

I can't add a separate vehicleset either but I'm finally getting the addon police cars chasing me during a police pursuit