Thousands of cars were trapped in the Motorway under the city of New New York for twenty-three years. It would take months just to go one mile (although the whole motorway just went in circles). The motorway had been shut down following a deadly plague spread by the effects of an emotion-stimulating drug, Bliss. A race of Macra had escaped from a zoo during this mass outbreak and was trapped in the motorway to prey on vehicles for food. However, the motorway remained locked up because the city above ground no longer had the power capabilities to unseal the exits. With help from the Face of Boe and Novice Hame, the Tenth Doctor opened the door and allowed the drivers to escape, but the Face of Boe's efforts to channel extra power to facilitate the opening of the Motorway claimed his life.
The New Earth cars had several features, including self-replicated fuel and bunk beds. They could also recycle waste into food.