US Patent 10311653 Hybrid vehicle

A use index IDX indicative of a degree of use of external charging is calculated and transmitted to a vehicle external system. The vehicle external system provides a service or imposes a penalty based on the use index IDX. In a case where the degree of use of external charging is determined to be low based on the use index IDX, if the vehicle external system provides a non-preferential service or imposes a heavy penalty as compared with a case where the degree of use of external charging is determined to be high, a driver or an owner of a vehicle takes an action by which the use index is determined to indicate a high degree of use of external charging. As a result, the use of external charging can be promoted.