dallison

As i am driving my 17 4 cylinder cvt accord, i notice in freezing temps in the winter that my mileage is lower than warmer and hot months. This is obvious in the colder climates with teh winter fuel and more dense air that it sucks in and has to move through.

I can average about 32-33 mpg in warm weather and seem to be down around 28 mpg in the cold. Where i would normally get about 34-35 and possibly 36-37 mpg on my commute to work, i struggle to get 29-30.

I wonder if a different motor such as a 4, 6, or 8 cylinder would have the same drop in mileage. Throw in a turbocharged or supercharged factory motor and would they experience the same drop or even greater.

I am not looking to buy a new car because of the drop, but i was interested in seeing any experiences or if there was research in this. I understand the warm weather folks may not notice the drop as much but they may also be getting the winter fuel. That part i am unsure of.

00TL-P3.2

I always attributed the drop to 'winter blend' fuel

horseshoez

iTrader: (2)

Part of the issue may be the fuel sold where you live; the other part is simple physics. Once the OAT approaches or drops below roughly 40°F, the colder intake charge inhibits efficient fuel atomization which in turn means the fuel mixture isn't as well dispersed in the combustion chamber. In theory at least, direct injection engines are at least partially immune from the atomization issue, but they still suffer from winter blend fuel.

Adding a turbocharger will not help your fuel economy for two reasons, 1) most turbocharger installations include an intercooler which drops the temperature of the intake charge back down to near ambient, and 2) when you're tooling down the highway at a steady speed on cruise control, the engine is off boost and the actions of the blower are pretty benign if not non-existant.

svtmike

My A4 gets a little over 27 mpg winter, a little over 28 mpg summer.

I keep the climate control on Auto/68 degrees, and usually have both the steering wheel and drivers seat heaters on in the winter.

horseshoez

iTrader: (2)

Is it safe to assume you have a relatively late model A4 with the turbocharged EA888 engine? If so then you have direct injection and it isn't surprising the delta between winter and summer in your car is so small.

svtmike

dallison

Interesting observation. do you have the turbo motor?

dallison

that is a good part of it. But, i am wondering what types and sizes of motors see big drops, gains, or nothing at all.

Of course hitting the remote start doesn't count since it sits 5-10 minutes without moving.

svtmike

SuperTrooper169

iTrader: (2)

So many factors go into this. I'd imagine the biggest is winter blend gas,. Second would be tire pressure decrease due to the colder temps. Third would be the increased use of electronics which would reduce efficiency, so increased use of headlights due to less day light, heated seats, heated steering wheels, etc.

As far as which engines are effected more, that's a really interesting question. I can definitely say my 5.7L V8 in the Charger has a decrease in MPG of about 2-3 MPG overall, but my wife's 3.5L V6 in the Rav4 really doesn't dip at all, maybe 0.5 MPG which is negligible IMO.

horseshoez

iTrader: (2)

Why do you think tire pressure is an issue; do you not adjust your tire pressure every fall and spring?

dallison

Do you really think using more electronics would cause worse mileage because of the higher drain on the battery?

dallison

Tire pressure should be checked at least once per month. The colder temps make you lose pressure quicker.

horseshoez

iTrader: (2)

Sorry, not buying. Checking tire pressure once per month is overkill and tires do NOT loose pressure quicker in colder temperatures.

SamDoe1

On long highway trips my Jeep goes from 30mpg in the summer to 22mpg in the winter because some genius at FCA decided that the rear axle disconnect should be disabled at temps below 37F.

Another big issue with cold temps is that engines run lean longer to warm themselves (and you) up. This is especially true when it's bitterly cold outside, my fuel economy plummets even further in the very cold.

SamDoe1

They don't lose quicker but they do lose pressure with large relative swings in temperature. The tire and rim expand/contract at different rates. I always notice a difference in pressure as the temp swings.

horseshoez

iTrader: (2)

Correction, engines run richer following a cold start, not leaner. The best way to warm up an engine is to start it, connect your seat belt, put the transmission in gear, and drive away (conservatively of course until the engine warms up).

horseshoez

iTrader: (2)

Yes, temperature swings will affect tire pressure, it makes no matter whether you're talking winter or summer. Around here the temperature swings are, if anything, greater in the summer. That said, just because it is -5°F on day and 30°F the next, that doesn't warrant changing your tire pressure every day.

ttribe

Move to Phoenix; problem solved.

knight rider

iTrader: (1)

I thought I was going crazy. Since it's been relatively cold in Central Texas my gas mileage has dropped from 23.9 mpg to 23 (so far). As you may already know, but for reference, the Q60 has a 3.0 TT V6. I have an air compressor and use it when needed, so tire pressure is not a factor.

01acls

It's the winter fuel and extra drag that's causing the drop in mileage in winter.

The winter blend fuel has 1.7% less energy than summer blend fuel. Longer warmup times uses more fuel not to mention the richer fuel mixture.

Drag on the car lowers gas mileage. The air is denser creating more drag, oil is thicker until it's fully warm... If it ever does get fully warm, grease is thicker in wheel bearings, alternator is working at max to power accessories... Creating extra drag on the engine... lowing gas mileage, lower average tire pressure creating more drag on engine, wet roads has more drag than dry roads, belts are stiffer.. creating more drag on the engine, etc.

​​​​​

SamDoe1

Yup, you're right. Sorry, typo.

It's more so the downward temperature swings that will affect things. I never said changing every day but checking weekly is wise. If you have a TPMS system, just page up and glance at the read outs every so often. Takes 10 seconds to do.

dallison

My interest is what size motors and it the they are boosted that experience differences in mileage.

horseshoez

iTrader: (2)

Ummm, what part of PV = nRT (the ideal gas law) shows a geometric progression as the temperature drops (hint: it doesn't). The fact is, if you set your tire pressure at 100°F and then the OAT drops to 70°F, there will be the exact same pressure drop as when you set you tire pressure at 30°F and then the OAT drops to 0°F.

01acls

The simple answer would be the motor that has the most torque to overall vehicle weigh ratio would have the lease loss in fuel mileage in winter. So probably the 4 cylinder turbo would be my guess because of power to weight ratio and it's tune to maximize fuel mileage.

​​​​​​Winter fuel wouldn't be a factor since that's the same for all car's.

To be fair hybrid vehicles would do best with winter fuel.

SamDoe1

I don't disagree with that at all.

That part that you don't understand is that the metal in the rim contracts a lot faster than the rubber in the tire especially if said tire is all season with rock hard rubber at low temp. When this happens, it can cause a loss of pressure due to a small breach in the bead of the tire or through the valve stem. I inflate my tires routinely and the pressure ALWAYS drops when the temp goes down rapidly.

svtmike

horseshoez

iTrader: (2)

You're right, I don't understand. Why? Because no such phenomena exists.

SuperTrooper169

iTrader: (2)

I'll just leave this here for those who say temperature does not effect tire pressure...

https://en.wikipedia.org/wiki/Cold_inflation_pressure

horseshoez

iTrader: (2)

I don't think anybody on this thread has said temperature doesn't affect pressure.

Aman

The pressure loss we see in our tires during winter is not caused by anything to do with the bead or valve stem. Not noticeably, anyways.

All else equal, any gas in an enclosure will lose pressure as temperature drops. This is (part of) the ideal gas law. This is why your tire pressure gauge or sensor will read lower in cold weather.

SamDoe1

It's wire braid just like the rest of the tire, I'm not sure if they are permanently bonded together but I've never taken a tire apart. If they aren't joined, then they'd shrink at different rates. If they are, they still may change at different rates as the rubber still has a lot of mass to it and can hold shape.

Ok

Absolutely.

dallison

I wasn't trying to figure out what causes this issue as we all have a general idea.

I was interested in seeing what motors see a great drop in mileage and which ones don't.

ttribe

[MODERATOR NOTE]: This is twice now the OP has asked his core question - Everyone please address the OP's question(s) rather than going off on a tangent.

SamDoe1

Ok well in that case I'll start a list for others to add to:

Jeep Cherokee Trailhawk, 3.2L V6 non-DI non-FI. Massive drop in fuel economy in cold.
Honda S2000 F22C non-DI non-FI, no clue don't drive in cold and don't bother measuring in the warm.

00TL-P3.2

^Adding to this: 2.7TT V6 F150. Mileage has been pretty consistent between winter/summer. Averaging 18-22MPG depending on how I drive.

The 2018 2.7EcoBoost went to dual-injection (direct & port) for a 10hp boost. Not sure how that will affect mileage.

SamDoe1

I guess I should also add that our temperature swings from "hot" to "cold" are rather vast. The temp in the summer is in the 80's-90's and the winter can be -10F no problem.

mrmako

My 2013 Volvo XC90 (3.2l gas, using only 85 Octane) gets roughly 23 MPG on the highway in the summer and 21 in the winter. but it doesn't help that I live at 7000 feet above sea level. I know that on a recent trip to the East Coast, ensuring I did not go over 85 mph, I could squeeze 24/25 to the gallon out, but that was more of an exception than anything else.

SamDoe1

That's a lot lower than I expected for something like that... On our last long summer road trip to CO we averaged 29.2mpg total in the Jeep. That was driving all 1200mi each way to/from Ouray with stops that had city driving at RMNP and off roading in the Ouray area for 2 days (low range, low speed, and high altitude murders your fuel economy...).

mrmako

Hell, even in Germany (with better quality gas) I only got 24 MPG. But I also would be on the Autobahn at 80-100 MPH. (at 100, I got about 17MPG. Can't fight physics). I think the 6 speed auto is geared for 65 MPH as it's cruise speed (under 3K RPM). I think a more modern 8 speed would get better mileage.