Why do I get worse gas mileage in the winter?

[SulkyAndroid17]

I thought the idea is the colder the air is The denser the oxygen, the better fuel/air ratio. Is it the ethanol added in the winter that is killing my mileage?

Your vehicle's engine is designed to operate with a certain ratio of air to fuel. Among other things, this is important because it ensures all the fuel in the cylinder is burned completely. During the winter, colder, denser air enters your engine. To compensate, more fuel is needed to obtain the correct air-fuel ratio.

 

[Speed Daemon]

Your vehicle's engine is designed to operate with a certain ratio of air to fuel. Among other things, this is important because it ensures all the fuel in the cylinder is burned completely. During the winter, colder, denser air enters your engine. To compensate, more fuel is needed to obtain the correct air-fuel ratio.

One thing that needs to be understood to understand how the whole shebang works is that all modern vehicles have computers that take input from sensors and calculate how much fuel to add to the mixture. Most of the time these are closed systems, where the computer constantly monitors the oxygen sensor signal to provide an optimal air/fuel mixture. The closed system doesn't care what's in the fuel; it adjusts the mixture to get the best feedback. Some of these are made specifically for "flex fuel" applications, where the amount of ethanol can range from 10% (normal gasoline) to 85% (E85). The computer can handle any mixture at or between these limits in both closed and open loop modes.

Thanks in part to electronic controls, Diesel and turbine engines can also run on a variety of fuels, ranging from plain kerosene and home heating oil to biodiesel and some alcohols, in addition to their own (and each other's) normal fuel product. Military forces have a long history of being able to use alternate fuels in their equipment, and right now the US military has bases that use JP-8 for everything from the kitchen stove to tanks, boats and fighter jets. Even civilian truck owners are starting to use civil aviation jet fuel to replace automotive Diesel fuel.

Pretty neat, eh?

 

[nickdalzell]

i have seen old diesels from the '70s run on things like kerosene and rumors exist if they will run on moonshine. often a late-model VW Beetle has been able to run on just about anything that would burn. and since it had catalytic converter delete my old Chrysler Fifth Avenue would run (and get slightly better mileage) on Avgas (100 octane low-lead)

The VW Rabbit (older generation from the 1980s) has been another popular car to be homebrewed to run on all sorts of fuels and applications by auto hobbyists. the Dodge Omni/Plymouth Horizon, similar in many ways to the Rabbit, another example. it's even had electric conversions.

 

[Speed Daemon]

When the government-mandated phase-in of catalytic converters and phase-out of high octane auto fuel started during the '70s, a lot of people with high performance, high compression cars without hardened valve seats did whatever they could to get their hands on avgas to replace what they used to be able to get at filling stations. But the government cracked down hard on that! It's amusing that it's happening all over again, but this time because Jet A-1 is cheaper than road-taxed Diesel fuel.

No gasoline engine will run on pure alcohol, no matter what the source. But I've heard about all sorts of gasoline substitutes that take various household hydrocarbons (often including mothballs), mixes them up into a witches brew that will at least get you out of a jam. No doubt MacGruber has blown himself up many times doing something like this! :hahaha: I can't say for certain that it works, but since actual gasoline is a precision-made witches brew of aromatic hydrocarbons, it seems at least plausible.

Diesel owners have enjoyed multiple sources of alternate fuels that will work, often quite well. The thing about both gas and Diesel motors is that what you put into them must at least come close to ideal octane or cetane requirements, or bad things (or just nothing) can happen.

By far the best flex-fuel power plant is the turbine engine. Because of its design, things like preignition are less of a problem than they are in piston engines. You can throw just about anything that burns into a turbine mill!

 

[vr4]

i actually have a large enough fuel system to run one of my cars on E98 if i wish. thats about as close to pure alcohol as you will get.

 

[Speed Daemon]

Yeah, that's one problem with using corn squeezin's as an automotive fuel. Ethanol has a low spatial power density compared to gasoline. It's also mighty costly to produce. The only reason why it's being used at all here in the US is because of factory farming and excessive corn subsidies that were never intended for factory farms, yet have been expanded under heavy pressure from the corporate welfare recipients.

If you're a US taxpayer and you're buying your E85, you've been swindled because you've already paid for it, often twice-over, with your tax dollars.

 

[vr4]

Well yeah. Imo corn lobbyists can die a painful, gasoline induced, fiery death.

But it is cheaper than c16 and makes more power to boot

 

[SamuraiBigEd]

When the government-mandated phase-in of catalytic converters and phase-out of high octane auto fuel started during the '70s, a lot of people with high performance, high compression cars without hardened valve seats did whatever they could to get their hands on avgas to replace what they used to be able to get at filling stations. But the government cracked down hard on that! It's amusing that it's happening all over again, but this time because Jet A-1 is cheaper than road-taxed Diesel fuel.

No gasoline engine will run on pure alcohol, no matter what the source. But I've heard about all sorts of gasoline substitutes that take various household hydrocarbons (often including mothballs), mixes them up into a witches brew that will at least get you out of a jam. No doubt MacGruber has blown himself up many times doing something like this! :hahaha: I can't say for certain that it works, but since actual gasoline is a precision-made witches brew of aromatic hydrocarbons, it seems at least plausible.

Diesel owners have enjoyed multiple sources of alternate fuels that will work, often quite well. The thing about both gas and Diesel motors is that what you put into them must at least come close to ideal octane or cetane requirements, or bad things (or just nothing) can happen.

By far the best flex-fuel power plant is the turbine engine. Because of its design, things like preignition are less of a problem than they are in piston engines. You can throw just about anything that burns into a turbine mill!

With diesel you can run bio-diesel, pure vegetable oils (with slight modifications, what Rudolph Diesel originally designed the engine to burn) or any processed natural oils such as animal fats or waste vegetable/animal oils, motor oil, most jet fuels (one, I can' remember which will destroy your engine) and kerosene to name some. You also have a wider cetane range that can be worked with on a diesel engine than octane range on a gas engine.

The real beauty of diesel is it has a much higher btu output which translates to more power and efficiency than gas or alcohol. The downside is being a fuel oil and not an aromatic petroleum distillate it is far more susceptible to cold temperatures but once you are at operating temperatures it will perform better.

 

[dibblebill]

Depends on the engine type- VW TDI's won't run nicely on a lot of types of diesel.

 

[SamuraiBigEd]

Some of the car engines are so tightly engineered they are a lot more particular.

Larger diesels don't have this problem, at least not yet.

 

[Speed Daemon]

With diesel you can run bio-diesel, pure vegetable oils (with slight modifications, what Rudolph Diesel originally designed the engine to burn) or any processed natural oils such as animal fats or waste vegetable/animal oils, motor oil, most jet fuels (one, I can' remember which will destroy your engine) and kerosene to name some. You also have a wider cetane range that can be worked with on a diesel engine than octane range on a gas engine.

Yes, it's really quite amazing how "green" Diesel was, and so far ahead of his time!

The real beauty of diesel is it has a much higher btu output which translates to more power and efficiency than gas or alcohol. The downside is being a fuel oil and not an aromatic petroleum distillate it is far more susceptible to cold temperatures but once you are at operating temperatures it will perform better.

Yes, the spatial power density of Diesel fuel is tops. This is especially valuable for tiny economy cars with limited fuel capacity. And I've seen some clever ways of dealing with the cold.

When it comes to driving pleasure, I'll still stick with the wide power bands supplied by the faster burning fuels used by my Otto motors, though!

 

[SamuraiBigEd]

When it comes to driving pleasure, I'll still stick with the wide power bands supplied by the faster burning fuels used by my Otto motors, though!

There have been some very big advancements in this field as well for diesel with prototypes from Audi and Volvo to name a few as well as some exotic race cars.

To quote Enzo Ferrari, "Horsepower sells cars, torque wins races." No gas motor in existence can come close to the torque curves and levels of a diesel motor!

 

[Speed Daemon]

To quote Enzo Ferrari, "Horsepower sells cars, torque wins races."

Mr. Ferrari said that to justify his use of 12 cylinder motors, which were exotic when that quote was made, and still are. As you know, the more power pulses per crankshaft revolution, the more torque. I agree completely, which is why I only buy cars with a minimum of 8 cylinders.

No gas motor in existence can come close to the torque curves and levels of a diesel motor!

You say that as if it's a good thing.

The whole reason why diesel motors have torque figures that are grossly disproportionate to horsepower numbers is because the Diesel fuel burns too slowly to spin them up to the 5252 RPM in the horsepower to torque equation. Sure a large turbo-Diesel motor can make some large torque numbers...until they quit at ~2000 RPM. But a force-fed gasoline powered Otto motor can produce the same torque numbers at two, even three times the RPM as their Diesel cousins.

What's more important is that the Otto motors will produce horsepower that Diesels simply can't make. Torque is just a function of horsepower, so one way or another it's all about horsepower. Horsepower and weight. Between the weight of the motor itself, and the gearbox with enough gear ratios to keep a Diesel "on the cam" on the race track, a Diesel would be self-defeating. Either it would be too weak or it would be too heavy compared to an Otto/gasoline motor. That's why Mr. Ferrari's V-12 exotics use the Otto cycle and burn gasoline. :burnout:

I'll grant you that it's impressive to watch a big rig driver shift up to 6th gear in just a couple of seconds. But when I see that in 6th gear the big Diesel is only moving at 20 MPH or so... :laugh: :slug:

Here's another POV on the subject.

 

[dibblebill]

And yet, winning cars at 24h of Le Mans the last few years were all diesels. In fact, last year's were turbodiesel hybrids.

 

[Speed Daemon]

And yet, winning cars at 24h of Le Mans the last few years were all diesels. In fact, last year's were turbodiesel hybrids.

Yes, it's quite interesting why they switched to Diesel power. Obviously in a race like that, fuel mileage is important. But it was actually a rules change, particularly one that mandated heavier cars, and thus making the heavier Diesel engine possible. (Restrictions like this are typically done when the most powerful cars are going too fast and crashing too often.) So the ballast and turbo penalty rules now favor the turbo-Diesel.

Time will tell how long the rules will give this technology the edge at Le Mans. Other interesting technologies in auto racing (the turbine powered Indy cars, the Chaparral fan cars, motors like Chrysler's 426 Hemi and Ford's 427 Cammer, and aero designs like the Plymouth Superbird come to mind) were banned as soon as they got a chance to dominate the tracks. Seems like the racing world is run by sore losers or something.

BTW, I mean no disrespect for your Jetta's turbo-Diesel mill. IMO it's an excellent, state of the art powerplant for the purpose it was made for. I just want to be fair to the American, German and Italian V-8, V-10 and V-12 motors, and the massive power they produce.

 

[dibblebill]

Oh, trust me. I understand. There's a big differences. Its like me and my fiancee comparing her Dodge Dart's little 1.4L Abarth engine to my 2.0L TDI. She gets 30 more horses than I do, but 50 less lb/ft. However, its like talking Granny Smith to Red Delicious apples. Some will favor one for various reasons, some will favor others.

 

[ItnStln511]

Don't some companies use different blends of gas in the winter and summer? I heard that somewhere and I'm not sure if it's true or not.

 

[Speed Daemon]

Don't some companies use different blends of gas in the winter and summer? I heard that somewhere and I'm not sure if it's true or not.

There are local EPA laws that mandate using less volatile gasoline mixtures in the summertime to help reduce smog. When I lived in the Chicago area, the IEPA had much stricter rules for everything automotive within large metropolitan areas, including Chicago. There are no such rules here in Madison, WI. No annual emissions tests, which is nice. When I travel to the Chicago area to visit my mom and friends, I buy my gas out of the regulated zones, and save 10-50

 

[ItnStln511]

There are local EPA laws that mandate using less volatile gasoline mixtures in the summertime to help reduce smog. When I lived in the Chicago area, the IEPA had much stricter rules for everything automotive within large metropolitan areas, including Chicago. There are no such rules here in Madison, WI. No annual emissions tests, which is nice. When I travel to the Chicago area to visit my mom and friends, I buy my gas out of the regulated zones, and save 10-50

 

[Speed Daemon]

That makes sense, thanks for explaining it. Also, does that mean that brand names don't matter in gas? For example, is BP gas any better than the gas the supermarkets sell?

My grandfather and uncles who were Phillips Pertoleum retailers in Texas and Arkansas would be the first to say "absolutely not", even though they were loyal to their brand. OTOH IME as a former retailer of Standard Oil of Indiana (at the time, "AMOCO") products I know that different brands do contain proprietary additive packages that do have some scientific research (albeit dubious) to back up their claims of being value-adding. Although I'm not privy to what's in any of them, I doubt that additive packages would offer enough real-world benefits to justify spending even a penny per gallon more for them.

To this day, I buy my gasoline based on only 2 things: the minimum octane requirements of my vehicles, and the best price that I can find. In my informed opinion, that's all that really matters. Unless you live in an area where you get unusually low octane gas (3rd world countries mostly), or have high performance cars, it's safe to ignore the first one. So my answer is "yes, but not enough to matter."

As long as we're on the subject of fuel additives, I should point out that buying most fuel additives is a waste of money unless you have a specific need. The ethanol in most gasoline these days is hydrophilic, meaning that it does the same job as Heet

 

[ItnStln511]

My grandfather and uncles who were Phillips Pertoleum retailers in Texas and Arkansas would be the first to say "absolutely not", even though they were loyal to their brand. OTOH IME as a former retailer of Standard Oil of Indiana (at the time, "AMOCO") products I know that different brands do contain proprietary additive packages that do have some scientific research (albeit dubious) to back up their claims of being value-adding. Although I'm not privy to what's in any of them, I doubt that additive packages would offer enough real-world benefits to justify spending even a penny per gallon more for them.

To this day, I buy my gasoline based on only 2 things: the minimum octane requirements of my vehicles, and the best price that I can find. In my informed opinion, that's all that really matters. Unless you live in an area where you get unusually low octane gas (3rd world countries mostly), or have high performance cars, it's safe to ignore the first one. So my answer is "yes, but not enough to matter."

As long as we're on the subject of fuel additives, I should point out that buying most fuel additives is a waste of money unless you have a specific need. The ethanol in most gasoline these days is hydrophilic, meaning that it does the same job as Heet