Most newer cars have a Serpentine multi-accessory drive belt. It is more efficient than the older multiple-belt system and may consume less space in the engine compartment.
The benefits of a Serpentine belt is that by using a single, wider belt the belt may be put under increased tension without being stretched. This will lead to an increase in the life of the belt. Also, having higher tension on the belt will reduce slip which will allow the use of lower-ratio pulleys. This will effectively reduce the load on the engine leading to increased fuel economy and available power.
If the Serpentine belt breaks, the water pump, power steering pump, air conditioning compressor and the alternator would cease functioning.