There are more than a hundred taxi companies in Washington, DC, each with their own unique livery: http://app.dctaxi.dc.gov/taxilist.asp?page=1&search=

It's one thing I've always loved about the city, as well as the sheer variety of cars used as taxis. It made the city distinct from someplace like New York. Apparently, my love of variety puts me in the minority. I really don't think this uniformity is necessary, but I don't live in the District and don't use taxis anyway, so ultimately it's not my place to say.

Anyway, a taxi reform bill passed this summer has mandated that all DC taxis will wear a uniform color scheme. The exact scheme is still being debated, and I'm not sure when the change will be implemented, but the days of Washington's rainbow of taxis are coming to an end.

Some of the proposed schemes:
http://www.washingtonpost.com/blogs/mike-debonis/wp/2012/12/10/behold-your-potential-d-c-taxi-color-schemes/

There was also talk of limiting the age of taxis (removing old vehicles from service), but I don't know if that passed as well. You can still find cars like Caprices and Roadmasters (both out of production since 1996) as taxis in DC, but the average taxi rider apparently likes new cars. Philistines.

Attached is a picture I took in May of taxis at National Airport; the back three rows with the orange and the blue/white cars are Virginia taxis but the first three rows are DC taxis.

They could do like in Italy: the taxis are all white. So then, in distance I can't distinguish them from municipal police cars.

At least the proposed color schemes are a little colorful.
Not like here in Brussels where taxis are black with a little yellow on the side:
http://www.xpats.com/sites/default/files/taxi-web.jpg

All their choices are ugly as sin. I don't know if I'd want to see them all yellow, and if they were to go to a single color scheme, my first thought would be the Orange & Black ones they had years ago.

Yeah, those are pretty ugly!

Is D.C. the largest American city without a taxi medallion system?

I guess the big challenge was to find a color scheme not being used by one of the cab companies. I didn't care for any of them. I remember the first time in DC in 1989-90 seing the different models used for cabs. I remember Pontiacs, Buicks, Olds, Mercurys, and smaller cars like Toyotas and Hondas being used as cabs. It was quite different than I would see in Philly or New York. It did add a little character to the city.

I also like seeing lots of different models used as taxi.
Here in Brussels it is often Mercedes, like in Germany. Many Skoda too now.
Some are much less common: I saw recently a Jaguar XF.

This sort of reminds me when Syrian border taxis that were used to travel to Lebanon or Jordan, consisted of a fleet 1970s Mopar cars. They were used until the late 2000s (circa 2008/2009) when they were replaced by crappy Hyundais and Kias. Not sure what was their fate when they were retired.

Here's some images I gathered of them:
http://members.virtualtourist.com/m/p/m/1043ad/
http://www.flickr.com/photos/hubbers/414988292/
http://www.flickr.com/photos/23234983@N06/2221400785/
http://www.flickr.com/photos/riwayat/198410262/
http://www.flickr.com/photos/lemonlulondon/4641853765/

Nice. Sad to see these replaced by Korean cars indeed

The orange and black ones belong to Yellow Cab Company, which is one of the largest companies. Yes, I know they're not yellow. I don't know why.

Here's one of the most surprising taxis I've seen; I'm terrible with Volvos so I'm not going to hazard a guess as to age (picture taken April 2011):

Saved the image too big the first time.