There is a thread on the 3 vs the civic
2006 Civic vs. Mazda 3
(^I know you started this one, but others might find it useful)
there is a big thread on what people are getting from the civic in MPG
What grade of gas? All gas questions answered! **Merged all gas threads**
Ithink most are in the low 30's, it depends on your specific driving habits. If you notice on the wiindow sticker, there is generally a range of mpg for city and a range for highway. I know my milage can vary greatly on my habits, driving aggressively I get about 33 MPG and driving carefully I get about 41 MPG, mostly highway driving.