Parking is not the main reason people go shopping, in fact it is well down the list, but retailers would make you think that it is the only thing that is between them and oblivion.
The best option, is to 'Go-for-Goldilocks'. That is change your pricing and/or restrictions to get the right number of cars in the right number of spaces.
You may have read a previous blog where I mentioned that if you have an overload situation, as you do in many suburban malls, having cars circulating in car parks does NOT increase the number of shoppers; you have shoppers plus motorists waiting to be shoppers, and hating the experience being provided.
The best way to approach parking for shoppers is to get the time restriction right and then to enforce that. You can get more shoppers by turning your parking bays over faster, not by increased queuing.
Free Parking Not the Best Way to Attract Shoppers?