it is better to rectify the deed by adding the clause of car parking as in the future the property title and ownership will be looked at what is your document.
it is necessary to specify the car parking with details of ad measuring area unit/slot No., even if it is mentioned in the sale deed that you have all the rights which was previously enjoyed by the owner with reference of previous deed no.
the car parking which is not mentioned specifically cannot be transferred legally , so it is necessary to correct it and register the deed of rectification for the proper title .
The existing deed can be rectified by preparing rectification deed by adding the clause of car parking with details and register it, once it is registered the deed of rectification will form part of your original deed of sale .
The process of mutation is for the land or property with house/ building where the flat is standing .
In your case you have one flat , the transfer on records happen when you register your sale deed so as the mutation.
literally speaking if your car parking has not included in the sale deed which is registered so it is not transferred from the previous owner in its legal terms.
actual transfer of the land beneath your building is conveyance , once it is done in the society or apartment owner's association the mutation also will happen in terms of ownership of the land in the name of the association or the society which formed by all flat purchasers/members .