depends on how frequently you need a car. I drive maybe 3 times a year. that's ~2k in gas/rent fees. that's less than insurance assuming each rental is for a week. never mind the cost of actually buying the car.
in practice I spend maybe 1k every year for cars. primarily for vacation. which owning a car wouldn't absolve me from spending.
... I run a junker. That is to say a car that will go the dump as soon as it requires any significant expenditure, and the combination saving of not having to finance it, and most years minimal or no repairs, and only needing third party insurance makes it significantly cheaper than renting.