What is this?

[KidWiff]

How long a drive is it to get to work? The engine will not attain full operating temperature for 10-15 minutes, and during that time the PCM (powertrain control module) will use a richer-than-normal mixture--it sends more gas to the engine. The purpose of this is to get the catalytic converter up to operating temperature as rapidly as possible because it doesn't do its job until it's hot. Frequent short trips without allowing the engine to fully warm means more driving with a rich mixture, and this can absolutely affect your fuel economy.

My previous car was an EcoBoost Mustang. I tracked mileage for the car assiduously (obsessively?). My work commute was 35 minutes of highway driving both ways, with a short (> 1 mile) drive on surface streets at the end. In other words, the perfect commute to maximize fuel economy. I regularly saw 32-33 mpg in the summer months, and 30-31 in the winter. The first year I owned the car I would drive it at lunch time to someplace local to get food. I noticed in the winter my mileage dropped to 28-29 mpg. After I started packing a lunch (or walking to a nearby sandwich shop) my mileage rebounded to 30-31. Cold weather makes a big difference with these cars, especially if you make a lot of short trips on a cold engine.

That's what i was thinking.... i'm just about 15 minutes to work (13 if we want to be exact) so not a ton of time to warm up on a cold day. I have a feeling this is the culprit. Took a long drive the other day (highway and back roads) and was seeing mileage like i had previously seen.

In the winter, when i'm mainly just back and forth to work, i like to try and get a long drive in one day on the weekends just to let the car get warmed up and then stretch it's legs for a bit. No real idea if that makes a difference long-term but... it makes me feel like i'm doing something. Thanks for your comments, much appreciated!

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[Mark S.]

No real idea if that makes a difference long-term but... it makes me feel like i'm doing something.

It can. As the engine cools between uses, condensation collects on internal engine surfaces. That condensation finds its way into the oil as water contamination. The oil can hold a certain amount of water in suspension, but at some point you have to replace the contaminated oil to prevent corrosion and abnormal wear. Frequent short trips increases water contamination of your oil and decreases the change interval as computed by intelligent oil life monitor. Occasionally driving the car long enough to achieve full operating temperature will increase the oil service interval because the oil will get hot enough to boil away the water.

 

[DadofTim]

According to AAA, winter blend gas is cheaper than summer blend gas because it is able to contain more butane. Butane is less expensive compared to other gasoline ingredients but also helps your gas ignite in lower temperatures. However, this added butane makes the gas slightly less energy-efficient.

 

[Mark S.]

According to AAA, winter blend gas is cheaper than summer blend gas because it is able to contain more butane. Butane is less expensive compared to other gasoline ingredients but also helps your gas ignite in lower temperatures. However, this added butane makes the gas slightly less energy-efficient.

Good point!

 

[Tigger]

That's what i was thinking.... i'm just about 15 minutes to work (13 if we want to be exact) so not a ton of time to warm up on a cold day. I have a feeling this is the culprit. Took a long drive the other day (highway and back roads) and was seeing mileage like i had previously seen.

In the winter, when i'm mainly just back and forth to work, i like to try and get a long drive in one day on the weekends just to let the car get warmed up and then stretch it's legs for a bit. No real idea if that makes a difference long-term but... it makes me feel like i'm doing something. Thanks for your comments, much appreciated!

Another thing to add to what @Mark S. and @DadofTim stated, is that in the cold tire pressure drops and causes more friction on the road, that is lower gas mileage. So, if you normally like it at say 33 psi, then you may need to add air.

 

[KidWiff]

Another thing to add to what @Mark S. and @DadofTim stated, is that in the cold tire pressure drops and causes more friction on the road, that is lower gas mileage. So, if you normally like it at say 33 psi, then you may need to add air.

Definitely keeping that in mind. thanks for the reminder!

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