Fuel consumption

Mazda3 4cyl.2.3 2007 9000mls.

Used to get22mpg cty 28mpg.hwy.Now16cty.23hwy.Dealer says its because of the 10%ethenol thats been added to reg.Are they woofin me?

Well you can expect to have reduced mileage when they mix in ethanol as it has less energy that gasoline, but even if it had no energy 10% could not make that much of a difference.

There are a lot of possibilities for reduced mileage and ethanol could be part of it, but I suspect that assuming the numbers are correct, there is something else going on. Any CEL’s?

Have your driving habits or route to work changed? A lot of people get great gas mileage while breakin in a new car.
Who’s driving the car makes a much bigger difference than 10% ethanol will. Ethanol has about 2/3 the energy of gasoline so 90% gas/10% ethanol mix should have about 96 to 97 percent of the energy of 100% gasoline.

Consumer Reports got 17mpg city when they tested that exact car, but 35mpg on the highway. The gas/ethanol won’t make that much of a difference, so try a 30-40 mile drive on the highway and measure your mileage again. Perhaps your driving habits have changed or your more agressive now? Also, are you sure you’re measuring the fuel consumption correctly?

After reading all your replies I guess maybe my foots to heavy.