Bad gas mileage in 2006 SE

[DainBramaged]

I have always monitored my gas mileage and highway mpg has always been ~21. Over the past year, it has slowly and steadily gotten worse and now I get about 15.5 at 70 mph. I get bad in the city also. Around 12.5. Any idea why?

[volvite]

Any changes to the truck? New tires? Have you changed the air filter? Driving style?

[twinblown]

I have always monitored my gas mileage and highway mpg has always been ~21. Over the past year, it has slowly and steadily gotten worse and now I get about 15.5 at 70 mph. I get bad in the city also. Around 12.5. Any idea why?

Are you determining the MPG by the trip computer or the actual miles traveled with a full tank?

[DainBramaged]

Any changes to the truck? New tires? Have you changed the air filter? Driving style?

The only thing I've done aside from routine maintenance is replace the radiator fan clutch. And I replaced it out of the annoyance at the noise level and the (irrational?) fear that the additional drag would somehow affect MPG.

Are you determining the MPG by the trip computer or the actual miles traveled with a full tank?

At first, only by the MPG trip computer, but then I did actual miles just to double check it, out of paranoia...lol.

[smj999smj]

Any chance your due for spark plugs? If not, I would check the basics, ie excessive fuel pressure, dirty MAS, restrictive exhaust, tire pressures, etc.