I found an interesting 2015 research paper from Montreal titled Identification of the minimum size of the shared-car fleet required to satisfy car-driving trips in Montreal, the abstract of which reads:

This paper examines how many cars would be required to fulfill all car driver trips in a metropolitan area if these cars were shared rather than privately controlled. It proposes a twofold analysis regarding the use of cars in urban areas using data from a large scale Origin–Destination travel survey conducted in the Greater Montreal Area in 2008 as case study. In a first step, the use of privately owned cars and their level of usage are assessed through indicators such as the proportion of daily time parked at home location, parked elsewhere and travelling. In the region, 27 % of the owned cars are not used during a typical weekday. According to the estimations, a car will, on average, be parked more than 95 % of the time. In a second step, the research simulates a full-scale mutualization of cars in the region. Cars required to fulfill all car driver trips observed in the survey are generated based on two hypotheses of access distance to the shared cars (250 and 500 m cells). It was found that between 48 and 59 % of the current fleet of privately owned cars would be sufficient to fulfill all car driver trips at the metropolitan level.

I like the phrase “full-scale mutualization.” I think many aspects of our lives could benefit from mutualization.