Save lives in Ambulance Side Mission
The Ambulance hasn't evolved much during the Grand Theft Auto series. It has appeared in every GTA game except GTA2, where a paramedic car (the Medicar) is featured instead. Ambulances are usually found outside hospitals, but will spawn on roads if multiple NPCs are killed, and two paramedics will revive the dead.
Paramedic side-missions can be activated when in the ambulance in all GTA III era games. These require the player to find, pick up and deliver patients to the hospital within a time limit. The difficulty increases with every level. Rewards (eg infinite sprint or extra health) are granted for achieving level 12. The mission is failed if the patient dies, the time limit runs out or the player leaves the ambulance for too long.