Taxis seem reasonably priced in Madrid until you hit some real traffic problems.

During the summer, when the city is filled mostly with tourists (all the locals clear the heck out then) taxis are incredibly swift, cheap and painless.

On a winter morning (or early evening) in rush hour, it's another story entirely. Gridlocks are not uncommon and journeys can be slow, expensive and incredibly frustrating.

You should be able to trust the concierge at the Intercontinental for some advice, but, in general, I would avoid taking a taxi during the rush hour.
You might like to check here for first hand data:
http://www.traficomadrid.com/Camaras...mapa=PRINCIPAL

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Spaniards love their cars - it takes bribery to get them to use the Metro (services are heavily subsidised)