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Mazda mileage

I have a 2009 Mazda3 hatchback automatic with the 2.3 liter engine. When new the car got 24mpg city and 31hwy. Around 12000 miles I had an oil change and tire rotation. Two weeks later I noticed a big change in mileage, 18mpg city. I checked the usual suspects tire pressure,air filter nothing. Took it to Mazda service had them hook it up to the computer, nothing wrong.

So for about four months I’m getting 18mpg city and 31mpg hwy. Three weeks ago got new tires and an oil change at 20500 and my mileage goes up to 21mpg.

Can somebody tell me what is going on with this car? I need some suggestions to run by the guys at Mazda service.

I have a feeling your car doesn’t like the ‘summer blend’ of gasoline for your area. The EPA has mandated a special summer blend of oxygenated fuels for use in certain areas to try to reduce smog. Some cars have shown to have reduced mileage due to these blends. The fuel stations go back to normal gasoline when Fall arrives.

My cars get better mileage on the summer blends. But others may not have it that way.

The fact that your highway mileage didn’t change suggests that it’s something other than the car. City mileage is drastically affected by driving habits. Some people who can spot red lights from a mile away can even turn the car’s gas mileage upside-down, that is they can beat the highway gas mileage in the city.

Are you commuting on a different route? Construction? School traffic? Bad weather?

A fast idle can also kill city gas mileage. Anything that makes the AC work kicks up the idle a little on many cars. Using the windshield de-fogger uses the AC and the heater at the same time.