The government is adding more and more every year of what needs to be on cars, and as a result they are weighing more and more, thats most likely why it gets worse mileage...nothing mechanically has changed since 2006, so it has to be something else. weight is almost always the culprit. look at how civics used to be powered by 90 h.p. 1.4 L engines and were amazingly fast (CRX), and now they use 140h.p. (approx.) 1.8L engines and get way less mileage... the answer? the crx weighs next to nothing and goes much faster than a new civic and gets better mileage but because of safety regulations the new cars have to have more airbags, crumple zones, etc.