We have had one car for the last 8 years. It has (mostly) been fine, BUT that's b/c I work from home and am introverted, so don't miss the car for spontaneous socializing or other activities. Also, our town does not have much in the way of recreational opportunities that might 'call to me' during the day (i.e., attractive parks, etc.) if I want to get out of the house. This city is TOTALLY car centric. No bike lanes (I wouldn't ride a bike on the main streets), very limited cab service (not unusual for a cab to take an hour to get around to picking you up b/c there are so few cabs), and very minimal public transport (buses) only on a couple of main 'arteries', not going to places I am likely to go. This situation has kept me close to my house when my husband is at work. It has forced me to become much more efficient in terms of running errands that need a car, but not problematically so.
The downsides have been that (even) I occasionally want to just up and go somewhere during a weekday, and can't without calling for uber/lyft (which I've never actually done, and don't know how this works....my impression is that it requires a smartphone, which I don't have). And we have had times when we had an emergency need for a vehicle and I couldn't get hold of my husband right away at work. Luckily, we have an 'on call' second car at my mother's house, and she was able to come on those occasions. But as she ages and on occasions at night, I would be much less comfortable calling on her for emergency help.
Ironically, I was just in a car accident that totaled our car, and the insurance company took THREE WEEKS to even start to deal with it, even though I was not at fault (it's now been 6 weeks and we still don't have the settlement check in hand). So we were on the hook for renting a car, until we decided to go buy another car after the first week of paying for a rental! That was REALLY annoying, and I have to admit that during the wait for the insurance company to decide whether our original car was fixable (it wasn't), I was kind of hopeful that we'd go back to being a 2 car household.
To be honest, if we lived in a city that had more attractive outdoor spaces (like all 4 of the previous places I lived), I probably would want a second car for my own mental health and independence. As it is, practicality and frugality keep winning out, so one car it remains.