The Russian word for taxi is такси. It is an indeclinable neuter noun, which means it never changes its endings:

Adjectives that modify indeclinable nouns must still occur in the case form required by the context:

Of course those are all possible in the plural as well:

Since Russians usually don't own cars, they use taxis a lot more than most Americans. This last summer in Kazan I used them constantly. To my surprise, when I bought tickets at the movie theater at Кольцо, I was given a discount taxi card:

I'm Scottish by descent, and let me tell you that we Scots hate paying more than we have to. For us, receiving a discount card is like... gosh... what can I compare it to? It's like getting free and painless high-quality dental work. I mean, you just can't think of anything better. I used that discount card all the time. And what's even better is that when you order your cab using your cell phone, they automatically pick up your number and when your taxi arrives, you usually get a text message saying that it has arrived. For instance, here is a text message I received:

It reads, “Black Hyundai #348 is waiting for you. The driver's number is 524-XX-XX.” Most taxis don't have a taxi sign on them, so that information is really convenient. Why the heck haven't American taxis picked up such a common-sensical idea?

Taxi service is reasonably priced in Kazan, but I wouldn't be surprised if it triples over the next year. Some regulations are going into effect that will increase the fees taxi drivers have to pay, which will probably result in less competition. I'm not looking forward to the change.