Originally Posted by
I-Like-To-Bike
If more people owned only one vehicle, rather than multiple vehicles, but still used that vehicle to drive the same annual mileage there would be zero fuel saved, especially if the single vehicle had to fulfill multiple transportation roles for a family such as towing, hauling stuff, transporting family for trips, commuting, etc.
In my experience it can play out in a variety of ways. Sometimes the same amount of trips are taken, just in one car instead of two. Sometimes fewer trips are taken, because coordinating various people's needs necessitates some shared trips and alternate means of transportation. Sometimes more trips are taken, in situations where one person has to get dropped off, then the car is driven back home and used for other errands, followed by another round trip to pick up the first person.
Even if the miles are a wash, though, there's no doubt that when we've been in this situation it has caused us to be *much* more conscious of our trips in terms of optimizing them as much as possible. Plus reducing the demand for production of another vehicle is a net positive.