OnVehicleDamageUpdate

new
    Float:vehicleHealth[MAX_VEHICLES];

public OnVehicleSpawn(vehicleid)
    return GetVehicleHealth(vehicleid, vehicleHealth[vehicleid]);

public OnVehicleDamageStatusUpdate(vehicleid, playerid)
{
    static
        Float:health,
        Float:damage;

    GetVehicleHealth(vehicleid, health);

    damage = vehicleHealth[vehicleid] - health;

    return CallRemoteFunction("OnVehicleDamageUpdate", "ddf", vehicleid, playerid, damage);
}

forward OnVehicleDamageUpdate(vehicleid, playerid, Float:damage);