VehicleLiverys

// Add this to its own class called "VehicleLivery.cs"
public enum VehicleLivery
{
    One = 0,
    Two = 1,
    Three = 2,
    Four = 3,
    Random = -1
}

// Then add this in its own class called "VehicleExtensions.cs"
public static class VehicleExtensions
{
    /// <summary>
    /// Gets the current livery of the vehicle.
    /// Normal liverys returns 0-3.
    /// No liverys returns -1.
    /// Non existent vehicle returns -2.
    /// </summary>
    /// <param name="vehicle"></param>
    /// <returns>The livery of the vehicle.</returns>
    public static int GetLivery(this Vehicle vehicle)
    {
        if (Game.Exists(vehicle))
        {
            GTA.Native.Pointer vehicleLivery = typeof(int);
            GTA.Native.Function.Call("GET_CAR_LIVERY", vehicle, vehicleLivery);

            return (int)vehicleLivery.Value;
        }

        return -2;
    }

    /// <summary>
    /// Sets the vehicle's livery.
    /// </summary>
    /// <param name="vehicle"></param>
    /// <param name="livery"></param>
    public static void SetLivery(this Vehicle vehicle, VehicleLivery livery)
    {
        GTA.Native.Function.Call("SET_CAR_LIVERY", vehicle, (int)livery);
    }
}

// Then instead of using it like this:
GTA.Native.Pointer vehicleLivery = typeof(int);
GTA.Native.Function.Call("GET_CAR_LIVERY", Game.LocalPlayer.Character.CurrentVehicle, vehicleLivery);
int livery = (int)vehicleLivery.Value;
// You would do:
int livery = Game.LocalPlayer.Character.CurrentVehicle.GetLivery();

// And instead of:
GTA.Native.Function.Call("SET_CAR_LIVERY", Game.LocalPlayer.Character.CurrentVehicle, 0); //or other values...
// You would use:
Game.LocalPlayer.Character.CurrentVehicle.SetLivery(VehicleLivery.Random);