 Japan has the world's largest hybrid electric vehicle fleet with 7.5 million hybrids registered .Japan also has the world's highest hybrid market penetration with hybrids representing 19.0% of all passenger cars on the road , both figures excluding kei cars., the U.S. ranked second with cumulative sales of 5.4 million units since 1999, and , Europe ranked third with about 3.0 million cars delivered since 2000.