I am not sure if it is the winter blend gas, the colder weather or a combination of both, but the gas mileage of my Maxima and my wifes Jeep Grand Cherokee have both plummeted about 10% the last month +. Her 2011 Jeep with the Hemi was getting about 18-18.5mpg in mixed driving and now it is down to 16-16.5 and my Maxima, which was getting 24.5mpg almost like clockwork has been dropped to 22-22.5 the past few tanks.

I read that winter blend gas contains about 3% less energy, but my cars have suffered a more dramatic drop than 3-5%. Is a 2-3mpg drop in mileage normal in the winter months? Do not seem to remember is dropping this much in the past...

 

i see an increase of 1-3 mpg in the winter due to the colder air i imagine. i hate the summer because i always see a decrease

 

As far as I know the additives to make cleaner emissions is not in the winter blend gas like it is in the summer gas. I believe what you might be experiencing depending on how cold it has gotten is that your engine users more fuel to warm up faster when you initially start it up. My car isn't warm and blowing air through the HVAC until I have driven about 3 miles now, when before it was warm by the end of my street. I am currently getting 24.1 mpg right now though due to an easy commute to work and a few long trips sprinkled in where there was little to no traffic at all. I look forward to see what kind of mileage I get when summer comes around.

 

That's funny I have the opposite problem although I don't mess with my intake any more.

 

granted if you count in that im idling longer in the morning to defrost windows and such, my mileage is actually lower. but for the actual driving portion I found myself struggling in the summer to get the same mileage I do in the winter

maybe i need to retract my statement, ive modded my car quite a bit since last winter...

 

There must be something wrong with my car. I have a 2011 Sport with 3500km on it and I got 16mpg on my last tank. Granted I'm a little heavy on the accelerator but I'm not flooring it all the time by any means. All city driving though trips of approximately 10km.

 

That seems about right. I get 17mpg with mostly city driving and around 23 with a 50/50 mix.

 

I also have the same problem. I generally get 23.5 MPG but as soon as the weather gets cold and stays cold my gas mileage drops. I am currently getting 22 MPG.

 

You're right about the winter fuel being less "energetic". Reason for this being that cold weather fuel is more oxygenated than in warmer months.

Now, a few other things...

1) Since winter fuel has less energy, takes more of it to complete a combustion cycle. This poses another problem since colder temps make gasoline harder to atomize in the combustion chambers.

2) Viscosity of fluids- colder temps mean that lubricating fluids both in the engine and trans mean more friction on rotating parts. Once the motor and trans are up to temp (190-200*) this isn't a problem anymore.

3) Warm-up on cold starts- this is a no-brainer.


Hope this helps answer some questions about poor MPG's in the winter months. One option is to go to 0W-30 oil instead of 5W-30. You might see a 5% increase in mileage.

 

I'm averaging around 18-19mpg this Winter, granted this wasn't been that cold compared to years past...can't complain.