Sure, it works in your context, you live in a city with 9 million people and you sometimes rent a car - fine. I live in a city 100x smaller. I literally don't know a person that doesn't own a car, or at least has access to a car.
The context actually get far more granular than it. I lived without a car for 25 years of my life, buses and trains were enough. But all it takes to require a car is having a home 3-4 km from the city center bus stops (which probably covers >50% of population). Unless someone likes walking 1h one way in -10 deg in winter to get to work each day.
A city 100x smaller is a city with 90k population. That's half of the population of the Upper West Side. And the UWS has an area of only 5 square kilometers. Unless you specifically choose to, you are not going to walk 3-4 km.
You don't live in a city. You live in a suburb.
This is a problem with city design, not city size.
That's exactly what "making cities work for people instead of cars" is all about.
It sounds like your city is about the same size as the city featured in this article, which has a population of 83,000.
-10deg winters are certainly going to put a stop to much walking or biking, regardless of whether that's Celsius or Fahrenheit.
Not much of Europe ever gets that low though. Edinburgh occasionally overnight, but it's rarely below about -4c / 24f during commute hours. Berlin mostly the same, Stockholm's maybe the only big European capital that gets to "walking for an hour stands a serious chance of killing you" temperatures for days at a time.