Big in Japan: Prius Fuel Economy

The Japanese fuel-economy ratings for the 2010 Toyota (s tm) Prius are in, and they peg the car at a whopping 89.4 miles per gallon. That gasp-worthy number makes that model of the Prius, expected to launch in Japan in mid-May, out to be the most fuel-efficient in the world by far. According to Toyota, the car achieved the rating under the country’s current testing standard, but rated 36.2 km/l (76.7 mpg) under a newer standard that takes effect in 2015.

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The fuel-economy rating of the 2010 Prius underscores the wide disparity in fuel economy standards around the world, as the model was given a rating of just 50 mpg in the United States. That’s up from 46 mpg for the 2009 Prius, which the U.S. Environmental Protection Agency certified as the most efficient vehicle of the year. The 2009 model rated 35.5 km/l (83.5 mpg) in Japan.

It’s unclear which standard is closer to the truth. According to an Autoblog post in March, the Prius performed better than 50 mpg in journalists’ tests, with about half of an unnumbered group of reporters getting more than 70 mpg. But most drivers certainly aren’t getting more than 80 mpg in regular driving. Autoblog Green goes so far as to call the Japanese fuel-economy numbers “insane” and “highly unrealistic.” Perhaps the future Japanese standard will prove more accurate, at least for the Prius.

In any case, under either country’s standards, the Prius is the most efficient commercially available car on the roads today. But the Prius and other hybrids will still need to continue driving prices down to remain competitive with regular gasoline cars. According to Green Car Congress, U.S. hybrid sales fell 44 percent from the same month last year, outpacing the 36.8 percent decline in car sales overall. JD Power and Associates last year noted that hybrids were losing market share to small, fuel-efficient gasoline cars, which are cheaper and therefore more attractive in a downturn.