The least expensive choice, by far, is the metro, but allows no luggage larger than a shoulder bag. Look for the large M marking the entrance. The city Metro system consists of nine lines and is clean, fast , modern and cheap - 10 cents buys a basic ticket or boleto. The trains can be unbearably crowded on weekdays between 4pm and 7pm. 6am-1am and Sun.
Exact fare is needed.
Peseros are small green and grey mini-buses, servicing passengers along major traffic and tourist routes. The driver waves his hand with fingers extended, indicating the number of vacant seats available. The basic sitio taxis in Mexico City are the plentiful yellow and white or green and grey VW Beetles or Datsuns. They run strictly by the meter, except late at night when the fare should first be negotiated. Tourismo taxis are larger with a hood over the meter and are used for hourly or day trips as well as private sightseeing.