I've never had a car and my roommate ditched his car shortly after moving in with me. It's a complete no brainer unless you live in a poorly-designed area[1]. He actually likes driving, but with a small fraction of the money he's saving relative to owning a car, he rents a sportscar once a month and we drive somewhere beautiful (one of our favorite choices is the oceanside cliffs near us).

[1] To be fair, the US wreaked havoc across its cities in the 60s and 70s, so it's a lot more common here than it should be.

My car sat for a year before I got it and it was fine. It depends on the car and conditions.

Much depends on what you do with the battery. Physically disconnecting goes a long way, trickle charge even further. But street parking and serious mothballing don't go well together, particularly when you never know ahead of time wether your next drive will be tomorrow or next year. There are cheap solar trickle chargers that supposedly solve the problem for street parking, but modern car electronics often require some rewiring to hook them up. In the end it's not an unsolvable problem, but a strong motivator to give in to reason and just take a rental when needed.

The battery was fine in mine too, and not disconnected. I had to jump it but it still had enough charge for the radio etc. and I've been using the same battery since.