Recently, environmental problems come to be taken prosperously, and the reduction of environmental effects is demanded in an automobile section. The alternative fuels for diesel engines have been also developed for emission regulations. In this study, the authors proposed and estimated the validity of the hybrid system, which combines a dimethyl ether (DME) diesel engine and a DME fuel cell for commercial vehicles such as buses and tracks. DME is adopted as the both fuels for good environment and high efficiency of the system. DME has received a lot of attention recently as a possible alternative to diesel engines for a little environmental effects and stable distribution. It has the same cetane number as that of diesel fuel and emits no smoke from diesel engines. The conventional LPG stations are possible to provide DME because of the same handling as LPG. The system obtains a driving power by diesel engines with DME combustion and at the same time generates electricity by a fuel cell with hydrogen generated from DME reforming. Carbon dioxide is collected and recycled to manufacture DME again in the system with a carbon free cycle. Amine is used to collect CO₂, because amine can absorb CO₂ at 40 to 60°C and emit it at 100 to 120°C. Amine can be also recycled then. The system in vehicles can reduce emitted greenhouse gases and obtain high efficiencies, and it can be also used for an air-conditioner, an audio utility or a light for long idling stops even if the vehicles have a refrigerator.