To further contribute to better fuel economy in hybrid cars, Aisin has developed an engine-cooling electric water pump  which is part of the new Prius unveiled by the Toyota Motor  Corporation. This product is the first domestically developed engine-cooling electric water pump.
This new engine-cooling electric water pump has three major advantages over previous mechanical-type pumps:
1) Because the pump uses a battery as the power source, it
can be operated on an as-needed basis, allowing optimal control of the engine cooling process.
2) Because this new water pump is battery - driven rather than mechanically-driven, it effectively reduces the workload of the engine.
Further benefits are a more simplified construction in the vicinity of the engine.
3) Easier and faster to replace because there is no beld to remove.