Here are our thoughts on the mpg...
The current 2012 2.0 engine gets 40MPG on the highway...
The new 2.5L with i-ELOOP on the mazda 6 is rated at 40mpg...non- iELOOP is at 38.
With 200lbs lighter on the new 3, the 2.0 should get about 45-50mpg?? as the 2.5 will yield 39-41mpg on the 3. Expect insane mpg from these newer models.
Now, keep in mind the consumer EPA average rating for Mazda is at 103%, so consumers are getting far better mileage than posted.