Different from traditional shortest-path or shortest-time routing algorithms, we provide PHEV drivers with a new routing solution of the lowest fuel cost.

Existing algorithms for gasoline vehicles cannot be applied to the cost-optimal routing for PHEVs because PHEVs can harvest energy by regenerative braking which may result in negative energy consumption on some road segments.

Existing algorithms for pure electric vehicles are not competent too because PHEVs have two power sources, i.e. ICE and EM. Thus, except selecting the route, the routing algorithm for PHEVs should also select the power source on the selected route.

This paper proposes a cost-optimal algorithm (COA) to deal with the challenges.