My n=3 sample from conversations with taxi owner/operators in SF is that they find it more profitable to rent out their taxi to other drivers when they themselves aren't driving it. This way, an owner can drive the taxi 8 hours per day and rent it to two other people for the remaining 16 hours.

The Camry Hybrid in the article is also a clear favorite due to the perceived high fuel efficiency, cheap and infrequent maintenance, and 200-250k mile battery life.