I checked mpg this morning, after a fill up, and it was around 16mpg. I used to get around 18mpg. I need to check my tire pressures, they are probably one of the factors for the lower mpg.

 

Blame it on the fuel companies and their winter fuel mix. The stuff they add for the environmrnt is what's getting ya. But check the tire pressure too if it's been a while, but again my bet is on the fuel mix. My 0.02

 

Tire pressure will typically drop about 1 psi for each 10 degree F. drop in temperature. I know that my tires are at least 2-3 psi softer than where I normally keep them and my mileage is down about 1-1.5 mpg. But it's not just the tires. As E1 stated, depending on where you live you may be getting the winter fuel mix. Also, this time of year we tend to let our cars warm up a bit longer than we do in warmer weather. Heavier traffic due to shopping for the holiday is taking it's toll on fuel mileage. Yada-Yada...

I used to keep a plot of my average monthly fuel mileage and it began to look like a sine wave after a few years... Up in summer, down in winter.

 

along with the tire pressure thing

the cold air is more dense. Because of this the truck would run lean if the computer didnt compensate and add more fuel... = mpg goes down.

my wife sees a diffreance of about that or ~50 miles on a tank of fuel between winter and summer in her bmw.

 

Check and see when/if your pumps went to oxygenated fuel. I go from 20 to 16 in my Tacoma V6 as soon as that crap gets released each winter. Started last week for me.

But wait, there is more!, MTBE, one of that additives used to oxygenate is now showing up in water supplies. What a great side benefit!! Most modern vehicles which are running properly are going to release similar emissions, wheter burning this dishwater or standard gasoline.

 

Yeah, winter mixes just started being used last week here, mileage went down about 2mpg or so.

It's the gas, but obviously check the standard stuff, air filter, tire pressure, yada yada.

Fink

 

really? ive found the complete opposite, ive noticed that as it has started getting colder, ive been getting better MPG. I usually fill up once a week, but since its been cold its been a week and 1/2 every week (and ive been driving the same, if not more)

 

THe MBTE that shows up in water tests comes from leaking tanks and fuel spills, (storm water run off from a gas station).

Burning of the fuel that has the aditive does NOT add addtional MBTE "emissions" to the air.

 

well mine has gone UP 2-3 mpg the last few weeks.. whats up with that? no a/c??

 

A tank which leaks MTBE-laced gasoline is much greater threat than a tank that leaks non-MTBE-laced gasoline. This is due to several factors:

1. MTBE is highly soluble in water
2. It only takes 20-40 ppb of MTBE to make a water supply undrinkable
3. The MTBE chemical compound is very resistant to breakdown in the absense of oxygen.

There is a reason it is getting banned by state and municpal governments. The fact that it gets burned well in the combustion chamber is nice, but irrelevant.