Depends on your definition of efficiency. Any ride service will drive more miles thus resulting in more congestion and more energy use than personal vehicles, because in addition to driving from point A1 to B1, they have to drive from B1 to A2. They get closer with density but never match. They will also always be more expensive to operate per mile because you need to cover the cost of the driver (human or machine).

The flip side is drastically fewer parking spaces needed, most of which can be located outside of the city core. And decreased costs due to fewer accidents.