Does weather have any effect on gas consumption? [Archive] - SaabCentral Forums

: Does weather have any effect on gas consumption?


saabvec
13th April 2004, 02:57 AM
I asked this because my gas milage has never been better :D My car used to only do 21.9 mpg at an average during the winter. A few weeks ago it gradually improved to 23.6 and currently it's doing 26.8 mpg. I'm sure there's nothing wrong with SID or the gauge as I manually calculated it and my calculation only had less than a mile difference than what the DTE read. No changes in driving habits, road conditions are the same and I have used the same route to and from work for 2 years now. What would cause this drastic change?

orion7144
13th April 2004, 05:36 AM
I'm not sure about weather but most states have laws that require addatives be added to the gas during the winter months that usually causes your gas mileage to decrease.

CallipNCSUsaab
13th April 2004, 05:43 AM
^ why would they do that? :o that is news to me!

Saba
13th April 2004, 05:56 AM
I suppose driving into a hurricane would have an effect on fuel consumption. :cheesy:

Larakin
13th April 2004, 10:23 AM
The weather most definitely effects gas consumption (it even says so in the user manual), in the winter (<32F or < 0C) your car consumes almost 10% more fuel than in the summer there is a nifty graph somwhere that displays the loss but I dont know where I saw it.

joshd2012
13th April 2004, 12:22 PM
There is actually a perfect temperature that the car will run at and give you the best performance. I usually feel it during summer night drives when the temperature is around 60 to 65 degrees. The car seems to pull better because the incoming air temperature is perfect. Gas consumption improves as well.

As for the winter additives, that is true. Some states do add crap to the gas to decrease pollution during the winter months. That is all I know about it though.

Castor Troy
13th April 2004, 08:14 PM
I get much better gas mileage in the summer than winter. The reason is, IIRC, when it's cold, gas will condense back into a liquid onto the sides of the combustion chamber, and won't ignite. To compensate, the engine has to run richer (use more fuel), and you will get worse gas mileage.

Thomthor
13th April 2004, 08:47 PM
Cold air is more dense than warm air, therfore the fuel injection system must richen the mixture to achieve the same air/fuel ratio. This does cause a drop in mileage, but it does add to performance.

CallipNCSUsaab
14th April 2004, 02:28 AM
are these "winter additives" simply reducing pollution.. or reducing mpg.. or rather BOTH?

Whats the point of reducing pollution BARELY if you are wasting millions of gallons of gas potentially?

orion7144
14th April 2004, 05:37 AM
The addatives are doing both.. Wasting gas and supposedly making the air cleaner.

TheKomoman
14th April 2004, 08:49 AM
are these "winter additives" simply reducing pollution.. or reducing mpg.. or rather BOTH?

Whats the point of reducing pollution BARELY if you are wasting millions of gallons of gas potentially?

You're asking politicians to consider REALITY? :roll:

We had the "reformulated" winter gas here for almost 10 years. Then, oops, somebody discovered it's actually a net INCREASE in pollution because of the decreased fuel mileage. Goodbye winter gas.

The refineries also change their mix a bit during winter to help with cold weather conditions and you'll sometimes notice a difference in the way the engine runs and the fuel mileage.

RED
14th April 2004, 01:32 PM
In so-cal, we get our low smog additives in the summer. The gas milage reduction is less than 2%. The tailpipe emmission reduction is up to 20% due to the fuel alone.

I have lived in LA (off and on) all my life, and the smog programs that began when I was in junior high school have made a HUGE FREAKIN' DIFFERENCE in the quality of our air. As a engineering student I got heavily into this stuff for awhile - combustion (smog) and fuel research have been the "engine" that has driven the high-tech engine development programs since 1976, ultimately giving us our high powered, ultra clean engines of today. Detroit had no need to do in-depth scientific research on combustion physics before this era. Car engines were low tech, and results that got more power were good enough by themselves. It was an article of faith among engine developers that a powerful engine running "in-tune" could not be made cleaner without reducing power. I know this for a fact, guys, not the newspapers: my uncle designed carburators, and his best buddy Ak Miller was a very early turbocharged engine developer for race and street.

Back to the first subject - cold weather will reduce gas milage substantially, just as Larakin pointed out. When the engine is stone cold, you can get fuel condensation, but that is a start-up condition only. Overwhelmingly, it is the air itself, which is more dense when it is cold - thus more fuel is required to maintain the correct air/fuel ratio. That ratio is a MASS ratio, you see, not volume. Any additional decrease due to additives is on top of the (much larger) decrease due to mass ratio.

Today, we get far more power per liter AND cars that are two (even three) orders of magnitude cleaner. So in this case, the politicians certainly have been "following the science", and dealing with REALITY.

Luv900
14th April 2004, 03:28 PM
wet after rain and snow will cause your car spend little more.

also graval and mud , tarmat is your friend.

Bad roads are you enemy and good roads are your friend

JonV
28th March 2007, 06:01 PM
The General Summer additive for Polution control in NJ, CA and in many other states year round are MTBE's. No longer used in NJ for one. They did have a decreasing effect on mileage:

http://www.eia.doe.gov/pub/oil_gas/petroleum/feature_articles/2006/mtbe2006/mtbe2006.pdf

john97900S
28th March 2007, 09:59 PM
Have owned a 900S since new in 1997. My spring, summer, fall mpg is 30-32. My winter mpg 26-28. It has been thus since the car was new.

BTW... I am located in NJ, USA so I am subject to the reformulated fuel with MTBE that is supposed to reduce air pollution.

JonV
29th March 2007, 03:34 AM
It's not unusual for average miles per gallon to go up in the summer, In the winter months I basically drive 220/250 miles per week averaging 23-4, Now that Spring is here I'll add 200/300 Highway miles per month on weekend trout fishing trips, in the summer 400/500 per month going to a Long Island Weekend House, then theres visits to family in VA/NC...now I'm getting 30+

Every one drives more highway miles in the the summer, more highway miles means higher average mpg. If I were just doing the "Commute" it would have gone down with the MTBE's being added.

Alex D
29th March 2007, 03:14 PM
Cold air is more dense than warm air, therfore the fuel injection system must richen the mixture to achieve the same air/fuel ratio. This does cause a drop in mileage, but it does add to performance.

Not only that but warm up is longer and the friction of all moving components of a car is higher in cold temps. Usually figure your mileage to be 2 to 5 mpg worse in the winter than in the summer.