A Prius taxi fleet has been operating in Canada since the first generation of the Prius. Here's the excerpt from the Vancouver Board of Trade has to say about the impact of converting some of the region's fleet.....
"If you want to get a very quick lesson, in the most dramatic fashion, of the power of low-emission vehicles, the next time you order a cab, phone Yellow Cab and ask for one of their Prius hybrids. You will get, during the course of your taxi ride, a quick lecture from the driver on how they have dramatically decreased their maintenance and their fuel costs, and increased the lifetime of the taxi. It's dramatic, it's right here, and when you see that little yellow Prius driving by, give it a honk and a thumbs up because it's on the wave of where we're going."
And the link in which this is contained......
http://www.wd.gc.ca/mediacentre/spee...20050120_e.asp
I've heard about this fleet before and have seen the same comments across the board. That's probably the reason for the desired conversion in NY.
For a taxi driver, it makes sense to save on fuel. A vehicle achieving over 50 MPG would definitely make sense for them.