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.
Then there's how these figures are calculated. Can we compare EPA's highway cycle to the EU's "highway" cycle? No. EU's highway cycle supposes the car at constant speed. As many Europeans can tell you, that's tough to get and real-world mileage figures actually are closer (and slightly higher) than the "Combined cycle", which is more comparable to EPA's highway cycle. Add the fact that EU's measurings are based on models and the EPA actually tests the cars. To make things even more complicated, the Japanese cycle is even different and focus on lower speeds.
Therefore, and as a rule of thumb, comparing EU and U. S. specifications is something that we can only do at approximate levels. However, we have the right to ask U. S. manufacturers to get us more fuel-efficient cars and their European operations show that they have those models. GM heard this when bringing the Astra and Ford did the same with the Focus and will bring the newer Focus and Fiesta stateside.
Here's some information about U. S. manufacturers we obtained (all conversions obtained here)
Saturn Astra 2009, 1.8-liter, 140hp, 5-spd manual - EPA's figures: 32mpg U. S. (hwy) = 38mpg IMP = 7.35 l/100km //
Opel/Vauxhall Astra,1.8-liter, 140hp, 5-spd manual - Official figures: 33mpg U. S. (EU combined) = 39.8mpg IMP = 7.1 l/100 km. This model doesn't offer significative difference.
Dodge Caliber, 1.8-liter, 150hp, 5-spd manual - EPA's figures: 29 mpg U. S. (hwy) = 34.8mpg IMP = 8.1 l/100 km //
Dodge Caliber in Europe: 1.8-liter, 150hp ,5-spd manual - Official figures: 32 mpg U. S. (EU combined) = 38.7mpg IMP = 7.3 l/100km. This model has slight differences.
In the case of Ford, we can't compare current models because they're different cars altogether, but the figures were very similar for the 2.0-liter versions of the 5-door model back in 2005. In the case of European cars, the figures are, again quite similar: European VW Passat makes 29.78mpg (7.9 l/100 km) and the EPA assigns 31mpg for higway (7.6 l/100km). Again, not a significative difference.