A radio car assigned to district patrol would be rather basic. Specialized divisions receive equipment more applicable to their daily duties. Traffic cars have radar and videocameras along with the specialized light bars. Emergency services, SWAT and the like all have their own preferences as well.
When you buy so many cars at the same time, contracts are let months if not years in advance. Wheels, mirrors, and all the minor fitments change while cars are on the production line. NYPD not only buys the cars, for each car they purchase a replacement set of doors, hood, trunk, wheels and bumpers. Dings and wrecks are repaired as fast as possible that way. Fleet management is a major undertaking requiring an entire division of people from mechanics to admin.
The three major expenditures in a police budget are salaries, fleet and facility maintainence.
G