NYC or otherwise urban moms, would you weigh in on this? I don't know who to ask, so turning to HB expertise as usual

Right now we have a beater 08 Civic and we keep the base for our infant car seat (Cybex Aton 2) permanently in the back seat of our car, and keep the actual car seat in our apartment. The baby is 8 months and is quickly outgrowing it, so I was going to get a Clek Fllo (heard they were narrow for small cars)--but, it sounds like from what I've read on Lucie's List and the like that convertible seats are big/heavy ordeals to lug around, and are really meant to be permanently kept in the car, which I'd love, but it makes me wonder if leaving one in there is asking for your car to be broken into. Does this happen? Is a car seat a juicy find for low life petty thieves, or is that ridiculous and they're holding out for the iPhone 7 someone left in the console? We live in a very nice neighborhood in Brooklyn, but I still see shattered glass, particularly on certain blocks, all the time. What do you think? Love to hear what you do/did, or if there's even a consensus on this.
ETA if it wasn't clear, we street park.