To start this mission, you must enter a Taxi, Cabbie, or Borgnine Taxi and press R3.
The goal of this mission is to find fares, pick up them up, and take them to their destination as quickly as you can. After dropping them off, you’ll get a bundle of cash. You’ll also have a timer to get that fare there; run out of time and the mission ends.
Additionally, your Taxi cannot get too damaged or your fare will get terrified and flee. To repair it, head over to a Pay 'N' Spray; you won’t be able to pick up another fare until doing so, and you’re still on a timer.
As you begin to rack up the fares, you’ll learn that you get bonuses after each five-fare streak, and bonuses for going to the destination extraordinarily quickly.
Do what you want with that, however. Personally, I do it when I immediately arrive at the area. Note that going to St. Mark’s in Portland will become a pain later in the game, so you may want to do it now.
The end result from this mission is getting a fair deal of money, familiarization with your locale, 100% Completion credit at one hundred fares (no need for consecutiveness), and the Borgnine Taxi will appear in Harwood near HEAD Radio after making one hundred fares.
There is one glitch that may help you out.
First, enter a Taxi and drive near a vehicle you’d prefer to do this mission in. I’d recommend using Banshees, Stingers, Cheetahs, Infernuses, the bullet-proof Patriot, a Rhino, or the Dodo (for fun).
In the Taxi, press AND HOLD R3 . Hold it until I say to release it. Press Triangle to exit the Taxi, then maneuver over to the other vehicle. Press Triangle to get inside and, once the radio is on for a second or two, release R3. The Taxi mission should start in this vehicle and be completely usable.