I recently replaced the air filter, flushed the tranny, and replaced the spark plugs with NGK G-power brand (.030 gap). However, now I'm getting worst gas mileage than before. I was at 25 mpg and within a week I'm at 24.1 mpg and it's still dropping. Anyone have any idea what could have caused this?

Thanks

 

That's not enough of a drop to start worrying. Fuel economy will fluctuate. It depends on the temperature, humidity, rain vs dry, traffic conditions, time spent at lights, acceleration, and dozens of other variables. But you know that, obviously.

Check your tire pressure. Scan for any stored codes. Keep driving like you normally do. If it still gets worse, check that one of your brake pads are not dragging. Replacing the air filter and flushing the trans are both good maintenance practices but I wouldn't expect gains in fuel economy from that unless the air filter had been completely cruddy. Worst case scenario you could put the old spark plugs back in to see if it gets any better. If that works then you know its the plugs. If nothing works try a fuel system cleaner or a different gas station.

 

check the gap on your plugs

FWIW - OEM plugs are best in these cars.

 

Will do.

Thank you for your help.