Car sharing is great for the occasional need for a car. Not Just Bikes calculated that if you need a car only once a week, car sharing (which is really short-term rental) is cheaper than owning your own car.

If you need a car for a longer trip abroad, you probably need a different kind of car rental, but the advantage is that every time you can tailor the kind of car you rent for the purpose you need it for. Get a station car or minivan for vacation, a tiny electric car for a short trip with no luggage, or a van if you need to move some serious stuff.