Streetcars are a type of mass transit first introduced in Simcity (2013 game). The system usually consists of trams which will pick up Sims at street car stops. The trams run through the centre of High Density Streetcar Avenues and will pick up low- and medium-wealth Sims.
Streetcars can be set up by placing a Streetcar Depot (30,000 Simoleons). From there, you must either use High Density Streetcar Avenues or Streetcar Tracks. You then have to place stops across the tracks for the streetcars to pick up the Sims. Depots must be placed near a road that can supply power.
Streetcars may seem like a brilliant idea at first, but they can sometimes result in more conjestion if they are not operating properly or are getting in the way of road conjestion. They also cost a lot to run. Many Sims will request that you build Streetcars if you have not done so already. Make sure you have plenty of money and are earning a lot of Simoleons per hour before you invest in one of these!