Do American cars in Europe sip less fuel?

Autobloggren reader Ron asked us one question: why does it seem that American cars in Europe sip less fuel? As he compared what look like identical models on either side of the Atlantic Ocean and consumption figures seem to differ.

First problem is finding two identical models. Then, pollution regulations are different in the USA compared to the EU. As a general rule, the EPA focus on exhaust air quality while the EU aims about quantity and has longer terms for other pollutants. As a consequence, injection systems might be tuned differently. Some people might think that gasoline is different. Europeans have two different types of gasolines: 95 and 98 RON which are more "premium" than the ones sold in the U. S. but, provided the fact that the injection systems are ready for the gas type, mileage should not affected (remember the "don't use premium if not needed"?). Perhaps the most important factor to consider are the differences between the mileage test procedures. The current EU test cycle is considered to give considerably higher results than the latest 2008 EPA test procedure. Finally, make sure that the numbers you are comparing are in the same units. Numbers from the UK are typically expressed in miles per Imperial gallon. One Imperial gallon is 1.16 US gallons.