Maybe the way I put it was not clear.
The enclusures are made to the specs of the sub and not according to the boot or anything of the car. There is nothing like box for Innova and box for Dzire. But it's like box for Focal 12", box for RF 12", box for Boston Acoustic 10", box for Polk momo 12".
The loud bass you are referring to is actually hollow bass. It's all boom boom and no acoustics. I guess you have to try out your sub in a correct box and that too sealed and then only you'll understand what I am saying.
But, say you are happy with what you have put in and it's output then just leave these technicalities aside.