I recently started paying attention to my mileage. It somehow went from 32-33 on the highway to 26. I also noticed that the overall mileage has down down through time. I don't change the trip odometer very often, so you can see over the last 3 10,000 mile sets that it's going down. Any thoughts? The car hasn't shown any codes and feels fine.

 

I did recently have the transmission fluid changed to solve another problem, but it's too recent to be part of this.

 

Part of your mileage drop might be from the change of seasons, and of fuel mixture (winter versus summer grade). Also, whether or not the fuel has ethanol, as the ethanol drops your fuel economy.

 

What problem did you solve with the transmission fluid change?

How many miles are on the car?

Did you notice the drop in gas mileage after any work on the vehicle, like new tires or new brake pads?