I'm giving you all a fair warning trying to find a cab in downtown can prove itself to be, a not so easy task. Oh, I for got to mention they WILL try to scam you. I know from first hand experience. They all say the same thing "Sorry my meter is broken", DO NOT FALL FOR IT. Ask them to turn the meter on.
The following are general guidelines for taxi fares in Detroit: Pick up $2.50, and $1.50 per mile thereafter. You may also see extra passenger fees, baggage fees, and airport fees in accordance with airport regulations.
From the airport to downtown your fair should not be more than $55.00, so please keep that in mind.
-If you do mange to find an honest cabbie, make friends and get his number.
-Ask them to turn the meter on, that way you pay the fair price.
-If they do leave the meter on, you can take advantage of situation, flip the coin by offering your driver what ever you think is fair ($5). If the cabbie complains tell them you would like to settle the situation with the police because having the meters off is illegal. FACT. Soon enough they back down and you should quickly leave.
If your staying in the downtown area you can use the Detroit People mover monorail system.