The Europeans are systematically cheating on auto fuel and emissions tests. You cannot believe the numbers the auto makers show off with the approval of the European Commission.
… What was once a gap between the mileages achieved on test tracks and real-world roads has become a chasm, according to a recent report from Transport & Environment (T&E), a green pressure group. Analysis by the International Council on Clean Transportation, a consultancy, of data reported by car owners in Europe shows that in 2013 fuel-economy figures “on the road” were on average 38% worse than those advertised.
The makers are allowed to test prototypes rather than production copies; they can remove mirrors, spare tires, etc; in the test the cars are driven with very gradual acceleration; they are run at the maximum temperature, which helps. The tests are simply nonsense.
We always hear that the Europeans are superior to us in every way and especially in anything about the environment. Don’t believe them and their cheerleaders.
This Wikipedia article tells more about the standards and the tricks. Wikipedia