That is using a different fuel economy measurement cycle...European cycle (unlike EPA) is notorious for being inaccurate.Saw a 23 May 2014 TopGear post by Vijay Pattni which says that "NX 300h fuel economy targeted at 54.3 mpg. That's "prius performance" and seems highly unlikely (or a miss print ?). ES 300h fuel Economy in the 40 mpg range seems more likely.
Actually, the latest US EPA protocol is very accurate for an AVERAGE driver. The protocol does NOT take into account a heavy foot, hypermiling, or places that have high speed limits.Too bad even in America the EPA can't ever seem to get the MPG rating right, comparing it to real world numbers it never stays in line with them
Example of above: http://www.edmunds.com/car-news/for...-six-vehicles-including-2014-ford-fiesta.htmlThis is why from time to time, you will see EPA ratings changed from year to year on the same car. This is because EPA went back and re-tested the car and thus had a different result from OEM testing. Classic example...Toyota Camry Hybrid (prior generation). Toyota (following EPA protocol presumably) testing showed optimistic ratings...after a year or two, EPA came back and re-tested themselves and lowered the fuel economy ratings. I am not sure if EPA punishes these OEMs "errors" or not.