Odd 'winter mileage'

[ViviTheMage]

Curious if there is anything someone else could think of that I should check. 01 jetta 1.8t , typically gets 28-30mpg in the summer (do the math on a fillup). So far I have been getting progressivly worse mileage. I bought brand new tires (they were needed) so it may be those...a bit sticky right now because they are new. I generally get 22 - 23 now.

New plugs, fuel filter, oil change, etc. Wonder if there is anything else I should check ?

 

[vi edit]

Oil companies switch over to a winter blend that affects milage. I've had cars/tanks of gas that had almost 50% less fuel milage than they would get in the summer.

 

[desy]

The cold makes a difference too
I see about 400 rpm higher til it warms up going down the HW.
It just slowly drifts down to about 2000 rpm

 

[CptCrunch]

Getting, on average, 5mpg less now then I did in the summer. Winter blend of gas, colder air, and with the warm/cold temperature switches possible tire pressure issue

 

[thomsbrain]

Winter blend gas hurts fuel economy, and cold starts do, too.

Actually, all things being equal, a warm engine runs more efficiently on cold air and cold gas, but when it is cold outside, the engine itself obviously starts colder and takes longer to get warm, which will really hurt mileage if you do a lot of little trips.

 

[Arkaign]

Check the PCV valve and O2 sensor. Sometimes if your systems aren't analyzing for EGR/etc correctly, the mixture can be very inefficient fueling the engine, causing poor mileage. Other possible culprits could be MAF/MAP sensor, but such a drastic drop in fuel economy, there must be something somewhat serious causing the problem.

 

[Uhtrinity]

Fuel blends, longer warm up times, colder air is denser resulting in more drag ...

My summer average was in the 70mpg range, winter has been between 45 - 50 mpg.

 

[InflatableBuddha]

Also, if you have to leave your engine idling while you scrape your windows, that certainly doesn't help the mileage. Just a necessity in winter unfortunately (at least for those who park outside).

 

[Arkaign]

Originally posted by: InflatableBuddha
Also, if you have to leave your engine idling while you scrape your windows, that certainly doesn't help the mileage. Just a necessity in winter unfortunately (at least for those who park outside).

Added to that, idling your car for at least a minute will help get the oil flowing to the top of the engine, it's a good thing to do before motoring off.

 

[ViviTheMage]

Originally posted by: vi_edit
Oil companies switch over to a winter blend that affects milage. I've had cars/tanks of gas that had almost 50% less fuel milage than they would get in the summer.

I knew about the winter blend, but I have never really felt it...seems so steep!

Originally posted by: InflatableBuddha
Also, if you have to leave your engine idling while you scrape your windows, that certainly doesn't help the mileage. Just a necessity in winter unfortunately (at least for those who park outside).

Ark said what I wanted to say haha. but yes, only if it snow does it idle for more then 20 seconds. Otherwise, I just take off around 10-20 seconds. I drive 25 miles TO work, 25 miles from work, so it gets warmed up well. Even school is about 14 miles.

Calculating mileage to see what gas costs me for the semester .

 

[SearchMaster]

That does seem a bit high for a mileage drop. I'm getting about 25mpg for the past couple of months, whereas I had been getting 27mpg in the summer. I'm in a warmish climate though (N. GA, lows in high teens).

 

[StageLeft]

Originally posted by: Uhtrinity
Fuel blends, longer warm up times, colder air is denser resulting in more drag ...

My summer average was in the 70mpg range, winter has been between 45 - 50 mpg.

Batteries do terribly when cold, though, so I bet that contributes to your worse mileage, unless your car actively heats them to a certain temperature (I was reading about a glider with lithium batteries that has a heater for them when they're cold).

 

[dainthomas]

corn squeezins FTL.

And now Oregon wants to have it year round.

 

[Uhtrinity]

Originally posted by: Skoorb

Originally posted by: Uhtrinity
Fuel blends, longer warm up times, colder air is denser resulting in more drag ...

My summer average was in the 70mpg range, winter has been between 45 - 50 mpg.

Batteries do terribly when cold, though, so I bet that contributes to your worse mileage, unless your car actively heats them to a certain temperature (I was reading about a glider with lithium batteries that has a heater for them when they're cold).

Batteries don't affect efficiency as much as performance in the Insight. The system does limit current draw and recharge until the pack is closer to room temperature. From a cold start I only get about 50% of what it is capable of and it takes a good 15 minutes for them to warm up. I have also read that the system uses a special pulse charge to warm up the pack.

My biggest mpg hit is definitely the warm up time while windows defrost, followed by fuel blend, harder to get lean burn and autostop as the engine doesn't get as warm, air density, higher rolling resistance of water / snow, etc. I guess the Insight has more to lose than your typical car. A heated garage would solve the worst problems.

 

[alkemyst]

how much you eat over the holidays?