Yes its a manufacturing fault in Cultus, I faced in mine as well, dealership changed both control arms and issue was resolved altogether there was no sound after new control arms were installed in my presence. At the dealership I met two other persons who was complaining about the same issue, Suzuki regional manager told me that there are number of cars facing the same issue and company has failed finding any solution to this despite changing the control arms. Then after a 1000 km of drive that sound started to come again though the intensity was low at that time as I was conscious already so I noticed. I don't think there is connection to the winter season in my case as it was hot summer in may/june when I faced the issue.
