I suppose the 41.9 mpg could be a typo, but I vaguely recollect that Japan has it's own version of EPA numbers, that are based on testing best described as ideal conditions.

Addendum: Here is the testing used:
http://www.jaf.or.jp/qa/answer/base/base8.htm

Ken@japan wrote in PriusChat that the Prius gets a 83.5 mpg in this test.

Something to strive for :-)
I cannot tell from the graph, but I'd love to know the acceleration rate.