An in-vehicle generator is caused to start regenerative generation when the regenerative generation is possible. This regenerative generation can decrease a generation amount under a vehicle traveling state where fuel is consumed and exhaust gas is emitted, thereby decreasing a load of an engine and amounts of fuel consumption and exhaust emission. The fuel consumption or exhaust emission to be decreased is computed and transmitted to a managing center via an in-vehicle wireless terminal. The managing center provides a driver with a reward such as a service corresponding to the decreased amount of fuel consumption or exhaust emission that is computed in the relevant vehicle. This system enables the regenerative generation to be returned to the driver as an economic value, motivating the driver to decrease the fuel consumption or exhaust emission. This thereby contributes to the conservation of global environment.