I own a 2010 Mazda3 GS with Convenience Package. It is the 2.0 litre engine and I have horrible mileage. If I ONLY drive highway, it is okay.. but from a full tank, by the time I get 400 kilometres on it.. the reserve light is on.. it's absolutely horrible. But I do love the car. Just wish it didn't use so much gas.
The Mazda 3 fuel warning light comes on after the car has consumed about 10 US gallon, so 400 km is about 10 km/liter, which isn't so terrible, but rather in the average range, no?
Well.. given that, that is all highway miles, I will say it is in fact pretty horrible. Most other cars in the segment get 6-8.. and even this year's cars.. 4.9-8 per 100km.. it just is a thirstier car.
However, it always drives and handles MUCH sportier.
Concerning this fuel consumption issue. A reply to some of the comments.
Firstly, the tank on the Mazda 3 is close to 55L. Therefore, if the car reaches 400km for a full tank, we're looking at 7.3 km/L and NOT 10km/L (although 10 isn't good to begin with).
My 2003 Sunfire with a 2.2L engine is currently running at 7.5km/L (close to the Mazda3 in question), which is equivalent to 18 MPG. These are horrible figures, since my car should achieve 36 MPG. But my car has a fuel system malfunction (Evap code), and when fixed, the MPG will return to normal.
My point is that this particular Mazda 3 has a malfunction somewhere that is causing the increase in fuel consumption.
But I'd like to point out that Mazdas are actually very thirsty cars, because I have owned a new Mazda 3 back in '04, and the MPG seemed close to 25-30 combined. For a 150 HP engine, that's considered thirsty, because my 150 HP Sunfire can give 36 MPG combined.
On a final note, I'd like to give my 2 cents on "breaking in" an engine. Although it is true that after the break-in period, the car will improve in HP and MPG, these improvements are very little (around 3%). And although the car in question has reached its break-in period (2000km), the real purpose of a break-in is to reduce premature engine wear.