A system for providing fuel-efficient driving information for a vehicle includes a fuel-efficient driving area calculation unit and a display unit. The fuel-efficient driving area calculation unit calculates a variable fuel-efficient driving area, which is divided into economical, semi-economical, and uneconomical regions, depending on the increase or decrease of the speed of the vehicle, calculates a current fuel efficiency of the vehicle, receives information about the type and condition of a road from a GPS, and adjusts the regions in the fuel-efficient driving area to prompt the driver to increase or decrease the vehicle speed in advance. The display unit displays the fuel-efficient driving area using information calculated by the fuel-efficient driving area calculation unit, and indicates the current fuel efficiency using the regions.