What are the taxi models in your city?
Here are my 2 cents.
In Toronto, Canada (my city) it's basically all the North American big cars like Crown Victoria, recently there are an influx of Intrepid, Lumina, Impala and even Camry's, after the city hall cracked down on old and broken taxis. There are minivans like Sienna, Caravan and Windstars. A number of old Caprice's are still running.
In Orlando I'd seen full size vans sitting 7 serving as taxis, quite economical I think.
In New York, 4 basic types (as in 1999): Crown Vic, Caprice, Venture and Odyssey/Oasis minivans; I always picked a minivan, all minivans had 5 seats only, the 3rd row was removed
Is it still the same now?
In Honolulu I'd seen a long wheeled based Mercedes taxi.
In Montreal it used to be small Japanese/German cars, not sure if it's the case now.
How about your city/cities you'd visited?