A sedan service is a transportation service that offers taxi-like rides in vehicles. Sedan services exist in many places, though the exact definition, along with regulations, may vary in different places. In some places, the term refers to a more luxurious service than taxicabs, while in other areas, it is a cheaper alternative. In most places, the ride must be prearranged, and a sedan driver is not legally permitted to pick up a hailing passenger like a taxicab. Also, most sedan services do not use meters like taxicabs, but rather charge by the mile, following the odometer.
Source: From Wikipedia, the free encyclopedia: http://en.wikipedia.org/wiki/Sedan_service