Toyota says it will voluntarily fix 650,000 Prius hybrids worldwide because of a glitch with their water pumps that can cause the cars to overheat or lose power. This is not a formal recall, because Toyota says the problem isn’t a safety issue and there have been no accidents or injuries.  A design flaw in the cars’ water pumps can create air bubbles that disrupt the flow of coolant, which can lead to overheating. However, Toyota says it will cover the cost to repair Prius hybrids whose water pumps can cause the cars to overheat or lose power.  The majority of vehicles affected by the flaw are in the United States. Repairs are needed on 378,000 Priuses sold in the U.S. between 2004 and 2007, along with 180,000 cars in Japan, 70,000 in Europe and 7,000 in Australia.  Prius owners who qualify for the repair will be notified starting in early December. Toyota will cover the cost of the repair at all U.S. dealerships, including more than $100 worth of labor.