Don't expect to hail a Decepticon battle taxi. They're more likely to shoot you than stop.
After the Decepticons took over New York city, the Constructicons altered the taxis that were abandoned for combat and patrol purposes. The only combat capabilities they displayed were weapons placed at the "taxi" sign at the top of the cabs. Their numbers, however, forced the Autobots Bumblebee, Sideswipe, and Sunstreaker into a retreat. Although he was lacking his right arm and weapon at the time, Optimus Prime decided to take action. The Autobot leader destroyed the taxis by running over them in vehicle mode. This is why you should never play chicken with a truck.