Providing this rating of "Parking Across Chennai" option at a whole city level does not make sense to me. That said, I would pick one public space that I use once in 3-4 months. I can now there is parking space in Chennai Central Railway Station.
That is not because of increasing paring spaces. The parking space is there because of getting rid of all taxis who were parking inside the station. I am not sure if that is good or bad. My rating is 3 because even though there is space to park a car, the place is really still far from being clean. Has stray dogs. Approach road have people lying on the pavement, hands extending in to the road etc. Far from a positive experience.