We're often asked why cars sold in Europe seem to be so much more efficient than those on sale in the U.S.
Typically, it's accompanied by the mention of some supposedly 80-mpg car sold in Europe--while the best U.S.-market vehicles barely crest the 50-mpg mark.
Now, Reuters highlights one of the main reasons for the discrepancy: Not only are European tests unrealistic, but automakers exploit loopholes in the testing, further blurring the lines between rated efficiency and real-world results.
Year after year, European sales figures have shown a bias towards higher average fuel economy and lower fleet-wide CO2 emissions.
In 2013, the average European car emitted just 127 grams of CO2 every kilometer--3 g/km below European Union targets for 2015 greenhouse-gas emissions.
To put some perspective on those figures, the sales-weighted average U.S. fuel economy of new vehicles has just crossed the 25-mpg mark--equivalent to 218 g/km of CO2.
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Some of that difference is down to the sort of cars people buy. Smaller vehicles and diesels are much more prevalent in Europe than they are in the U.S, and both typically lead to more fuel-efficient vehicles than large vehicles with large gasoline engines.
Cars really are more efficient "over the pond," then, but many come with performance (and size) compromises that few U.S. drivers would be prepared to live with.
Classic Volkswagen Beetle Convertible & 2012 Volkswagen Up minicar, Catskill Mountains, NY, May 2012
Discrepancies between European and U.S. numbers extend far further than that, however. Some of it is down to how cars are tested in Europe--the New European Driving Cycle's test procedure is both shorter and slower than the EPA's procedure.
The European "Urban" test, for example, is 13 minutes long--the EPA's city test is 31 minutes long. The "Extra urban" test takes 6 minutes, 40 seconds; the equivalent EPA highway test is 12 minutes, 45 seconds.
Speeds are different too. During that 13-minute urban test, the highest speed attained is just over 30 mph, and maintained for only 12 seconds.
The rest of the test is made up of slow acceleration and deceleration, while around 2.5 minutes is spent stationary--meaning cars equipped with increasingly common start-stop systems use no fuel at all for those minutes.