I purchased my '05 Limited Xfire approximately 3 years ago. It now has 36K miles on it. I regularly switch between midgrade and premium fuel--89 and 93 octane. I was consistently getting 25-27 miles/gallon. Over the past couple of months I have been getting 23-24 miles/gallon. I recently replaced both front and rear tires on the vehicle, but I am having a hard time believing that the brand new tires would adversely affect the gas mileage in this way. My driving habits and locations have not changed.

Does anyone have suggestions as to why my gas mileage has been reduced?

 

Winter temps, more ethanol in gas, sticky brake rotor or maybe tire pressures?

 

Don't know where you're located, but if it's only been the last couple of months it may be because of the cold winter weather. My mileage drops off dramatically in the colder temps, my motorcycle will drop 20% by the time the temps get to around 35. Add to spinning the tires on snow and ice and a drop is normal.

If you've noticed a loss in power you might check clogged injectors or maybe a bad catalytic converter or something on that order

 

Cold weather gas formulas give less mileage. Tires can affect mileage by 10 percent if you had all weather and went to summer tires. Summer tires stick much better and give you less gas mileage. Hope this helps.