Colder weather has zapped my mileage to 44mpg

What the other guy is trying to tell you is that that is the EXCEPTION, not the RULE.

Consider yourself clued...

 

Cherry-picking trollage... Look at the overall color - dark blackish/red-black vs red with just a hint of black.

 

That's exactly what I said. CR is good for a rough idea of the whole picture. Really careful buyers hardly pay much attention to CR these days...

 

Yes, I'm clued. It is too bad that the Prius is the exception, not the rule! I'm looking for a car that follow the rules...

 

Then you made a big mistake buying a Prius and we found the fundamental problem.

How could this car follow the rules:
- Mostly does not use normal friction braking
- Try to reuse energy that is normally lost
- Use a less powerful than normal Atkinson engine
- Use a more efficient engine than normal
- Try to keep this engine in its peak efficiency instead of normally crossing that peak efficiency only casually
- Use a weird outside shape to be abnormally aerodynamic
- Abnormally use a bigger engine than the previous generation... to save gas...
- Carry additional weight in form of a 100lbs battery... to abnormally save gas...
- ...

.

 

We are looking for owners who follow the rules...

You complain about your Prius not meeting your expectations compared to your previous vehicles, yet you don't show us either the data from your Prius or from your previous vehicles.

It's been over a month and there's almost nothing to show for it.

Unless we see what complaints are actually about, what's the point?
.

 

You should care since you're using it as a comparison/benchmark. You should either blame the test methodology or your driving habits and conditions, which are nowhere near what the EPA cycles simulate. The numbers are only as "good" as the tests. I posted about this before. I already called into question your earlier mileage claims, a small part of which could be inflated by likely Honda odometer error.

First off, don't you think it's possible that over a 6 year run of a vehicle that a car maker, its suppliers and their suppliers might make some process or parts changes? They could include a change of suppliers, cost reduction, reduction of assembly error, labor reduction, change of assembly method, quality improvements, etc. Some of that is done in response to defects observed at various stages of manufacturing or based upon complaints or warranty claims and possibly even spikes or trends in demand for certain parts or repair work.

Besides that, the workers and managers change and plants be taken on or offline or added to produce a vehicle. All this call happen even within a model year. Per No Satisfaction - Toyota - Georgetown - Car Factory | Fast Company "Toyota's assembly lines make thousands of changes a year to how the work is done. "

The above is assuming the car is static, which it's not. The 06 model year got the biggest changes from the previous w/additions like the aux input jack, higher res MFD, different tail lights, different dash material, backup camera, and the cassette deck was ditched. You can see more at https://priuschat.com/forums/knowle...andard-optional-equipment-some-countries.html.

Hobbit figured out why MFDs tended to fail on 04s and 05s, which CR respondents could be attributing to audio system or electrical on the 04s. After all, on the 2nd gen, the radio was all controlled via the MFD. See Prius MFD and the update at Prius MFD.

I guess you never bothered to look into how the survey and study is conducted. You can read about it at Reliability histories (unfortunately, some of the text is a bit behind the currently reliability charts). CR sends out a survey asking about "any serious problems they had with their vehicles during the past 12 months that they considered serious because of cost, failure, safety, or downtime, in any of the trouble spots included in the table below." They ask the make, model and mileage of the car.

Let's make a hypothetical case for the audio system. Let's say 30% of Prius stereos tend to fail once they hit ~5 or 6 years old. Well, that would make a huge blip only in 5 or 6 year old Priuses. Once most of that 30% group either got it fixed or did nothing, we'd see it ripple thru the rest of the year's surveys, assuming no improvements were made to the stereo's reliability.

Your brother's sample size is tiny. He's had 4 or 5 Audis of different ages and at least two different models. IIRC, there has to be at least 100 responses for a given model year of a car to not be labeled insufficient data.

 

After 51 pages in this thread here is a summary of what I have come away with.

1. The 3rd Gen Prius does suffer a MPG hit in cold, miserable winter
weather.

2. This hit can either be worsened or mitigated by the driver's style.

3. Even at excessive speeds, and yes over 65 is excessive, the Prius
still gets decent MPG's!

4. When driven as a hybrid using the tips many have shared here,
the mileage is far better than any other car on the road.

5. When Spring finally arrives, along with the usual jump in gas
prices, the Prius will once again rock the MPG's, even when
driven poorly!

6. None of this matters 'cause Audi is awesome and Toyota and CR
sucks!

 

So, we know there is more aerodynamic drag in the winter time. I'm wondering why the engine appears so much less efficient in winter temperatures. Is the Prius engine so efficient that it actually burns more fuel in the winter temps just to maintain the proper water temperature at highway speeds? I thought at highway speeds there was plenty of waste heat but it appears that may not be so. I ran an errand last night that took me on the freeway at 70 MPH and I didn't turn on the cabin heater until I was on the freeway, at 70 MPH, and my SG showed the water temp at 190. The fan speed (was set to Auto) went up to 5 bars and as expected the air was very nice and warm. What surprised me was the water temp within 5-6 seconds dropped to 185. To me, this showed the ICE doesn't produce as much waste heat as I thought it did. It would be interesting to put my SG on my Odyssey and see if it pulls the water temp down when the cabin heater is turned on. Probably not as much if at all and part of the reason would be a bigger engine and more coolant on the Odyssey. I just wonder how much extra waste heat the Odyssey produces under all conditions.

If the ICE then burns more fuel than necessary for motion, where does the additional HP produced go to? Does it modify the timing to burn more fuel while not increasing the HP or possibly adjust for it in the CVT? It is an engineering marvel I'm very happy with but I would be nice if they could solve or improve the cold weather performance.

 

What happens is the engine has to generate more power ... IF you hold the same summer time speed. As the power required goes up, the engine is forced into less efficient operating modes:

• more fuel is needed - so the intake valve closing happens sooner to keep the fuel-air charge higher. This increases the energy needed to compress the fuel-air charge.
• transmission and tire drag increases - the colder temperatures means the oil gives more resistance and the tire flex loses heat quickly and gives more resistance.

Bob Wilson

 

Add in cabin heat requirements and the engine will not run at optimal temps due to all the heat going into the cabin.

 

At the risk of stirring things up again, we had our first warm day (45F) since I bought my car - and my MPG jumped considerably. I had a tripmeter displaying 45mpg (and had been fairly steady there), and the first 12-15miles today were enough to bring that average up to 49. After gassing up and resetting the tripmeter (and having a slow start that gave me a low mpg to start with), my MPG went all the way up to more than 52MPG displayed - with snow tires...

Based on what I saw before installing the snows, I'm starting to think that there could be a steepening of the curve when temps change from mid-40's down to low 20's or teens. And that steepening may be bigger at higher speeds.

 

The temperature here has been climbing and just made it to the freezing mark. As a result, I'm seeing 50's again too. The displayed average for the tank so far (currently, just shy of 400 miles) is 49.5 MPG.
.

 

EPA or EU norm estimates of fuel consumption are intended to be used as a reference, an indication of how the car behaves in terms of fuel consumption in standardised and controlled conditions. Since all cars are tested in the same way, if a car has higher EPA numbers/lower EU norm FE numbers than another, it means that *relatively* to another car with lower numbers it will perform *on average* better.
In an extreme case, a car might be designed to get the best possible numbers when tested according to EPA or EU norm requirements. It might be a total gas guzzler in other conditions.
Beating an EPA FE number might be a nice game, good for you if you can manage to get better numbers, but having higher numbers in winter does not necessarily mean that Toyota is selling you crap.
*all cars* have a winter MPG hit (some cars more or less than others, certainly - it depends on a multitude of factors) and for *all cars* all the people I know do agree that FE numbers in ads are only relative and not absolute values - all people I know (at least in Europe) will never believe that their car will actually achieve the FE numbers that car manufacturers have to show, by law, when selling a car. And thank goodness there is a standardised way of measuring it in US/EU, otherwise we would not know if a car *is* a gas guzzler or not relative to another!
If in the EU and in the US a car gets the best numbers possible among all cars sold in that country/area, it is very likely it is the most fuel efficient car available.
E.g. there are already a few cars sold here in Germany (diesels, that is) that show "outside town" fuel consumption numbers better than the Prius (3,4 vs 3,8), but then...how do they fare in town? (BTW for that same model I think it was 5 vs 4L/100km - would that car exactly do 5L/100km in town or 20% more? does the Prius do that? I don't know - on paper the Prius in Town is still the most efficient car, even of other diesels and smaller cars) and how much more tax do I need to pay for that car - in Germany I pay 36€/year for the Prius a diesel with CO2 of less than 120g/km (if available) and same engine displacement will pay 171€ or about 80% more... So what should I buy?

To finish off - my Volkswagen Polo 1.4L TDI had a hit of about 1L/100km in winter compared to summer in my commute (5 to 6L/100km) - about 20% more. Winter tires and heater were the main cause. Did I ever think for this reason that VW sold me a crap car? Not at all. I had other reasons for that (rattles, being one of them - VW does not or did not have good quality, I can assure you)
I heard only one case (from the Toyota vendor....) in Germany of a guy suing BMW because his turbo charged diesel engine was consuming up to 50% more fuel and just as much oil, than advertised for that model, in summer climate...
That a car consumes 10%-20% more in winter is nothing to talk home about and well accepted - there are reasons for it. 50% more, the dealer would have 5 interesting minutes chat with me.
That a modern diesel car of the same size/weight and power in winter on an highway at constant speed is/might be better than a Prius, that might well be.
After all the Prius is not a normal car and I would not expect "normal" behaviour from it.
Moreover, what is the lifetime MPG of the Prius? that is what counts the most.
If the summer consumption does not reach EPA numbers (are you driving in the same EPA rating conditions? all the time? really?) then you could sure sue Toyota. You would have to give them numbers based on you driving the car in the same EPA testing conditions and if you get an higher number, sue them.

BTW: I am getting about 20km/L - 5L/100km right now (see below PS2) compared to 4.7L/100km in Sept./Oct. timeframe on my commute: this is still better than what I would get with my Polo in the same conditions (5.5L/100km on average in winter). Moreover, such a big car, with 130HP, 1400kg heavy that achieves 20km/L in town in winter is to praise, not to brag about. When I tell these numbers to my friends and colleagues I get utter silence because they are realising how bad their cars are in comparison.
Getting 44MPG-18km/L on a highway with this car in winter in the US is in many ways exceptional, compared to what is out there. Especially in the US.
If I wanted a better consuming car of this size, weight and comfort, for my usage pattern I would be at loss as there is, unfortunately, no alternative solution on the market. At least according to my needs and expectations from a car.

PS: the 42MPG you see below in my signature contains several high speed (well more than 120km/h) highway trips (300km or more) and it is since end of September when it started to be cold - this is a calculated number not MID. If I don't get something more in the direction of 4.5-4.8L/100km in the same conditions but in milder temperatures (say above 10C), rest assured that Toyota will hear from me, but trips in my commute with 3.4L/100km have been achieved 3 times in September, so I am confident that I will not be disappointed.
PS2: my commute consumptions averages (MID, not calculated) since getting the car on Sep.23rd have been (all numbers L/100km): Sep. 4.6, Oct. 4.8, Nov. 4.9, Dec. 4.95. On Nov. 11th had to install winter tires. Break-in (2500km) beginning of Nov.
For reference, the *7-year old* Polo (MID - add ?% - I don't know the MID error on the Polo) from Aug. 17th till Aug. 31st achieved 4.78, and in Sep until I got the Prius, 5...seems the Prius is doing pretty good to me...
The Polo, FYI and to put things in perspective, was a turbo diesel 1.4L engine; compared to the Prius the Polo had: 26% smaller engine, 80% less HP (75 vs 136), 20% less weight, 185/60R14 vs 215/45R17 summer tires (!!!), declared fuel consumption of 4/4.5/5.6 vs 3.8/4/4 (sub-urban/combined/city) of the Prius (I am not too sure the numbers are tested under the same EU norm since there are about 7 years apart.)


I hope this post is of help and I still don't understand what there is to complain/discuss about. It would be instead interesting to know on "average" what is the MPG hit people are getting. On average. Worldwide. On average.

I got 7% "hit" on average, on my "standard measurable repeatable-traffic/driving conditions commute", since Sept. with Winter tires, no grill blocking, car parked on the street - is this of any help?!?!?

 

Yet another data point from my 90 mile drive this week:

• Cold engine start
• Not round trip, but no elevation change
• 6300 feet elevation
• Dry roads, minimal wind, I think in my favor
• About 50F Ambient
• 55 mph - 63 mph
• Tried not to exceed 2400 rpm

SG result: 62.2 mpg

Oddly enough, this result has moved me towards IK's viewpoint that the Prius takes a winter hit in mpg that is greater than conventional cars, although probably not for the reasons he guesses at.

We have known for a long time that the Prius is *relatively* a poor performer at high speeds. ICE demand of much over 20 kW often takes us off the best part of the performance curve. This leads me to suspect that in the cold of winter on wet or snowy roads, we reach the sweet spot of Prius efficiency at considerably lower speeds, perhaps up to 10 mph slower than summer.

Some people like IK who refuse to slow down see the MPG hit; drivers like me see much less of it. Put another way, all devices, including Prius, have their inherent points of strength and weakness. Most of the people who frequent PC know the Prius strenghts and adapt their driving to take advantage; the occasional person stubbornly lives in the Prius weak zone, cannot understand why the car will not adapt to *him*, and becomes a whiner.

 

I'm going to second this... although *winter* in NC is not the same as winter in the North East, North West, we still saw colder temps than previous years throughout December/January. Most mornings, I started off in the upper 20's F for my commute, and ended it in the lower 30's F. Comparing that to September with 60's-70's F. I'm not seeing much difference in my tank averages. You can see them specific to the prius here. Moreover, I didn't see much difference in trip averages either. I still averaged about 60 MPG for the trip to and from work, except on those days where it was both cold AND having winds that topped 10-15 MPH. The wind seemed to make more of a difference than the colder temps.

The biggest hit through December, was the fact that I didn't drive my normal 3/4 of the mileage. It was closer to 50/50 with my wife, who travels faster than I do, and is more of the gas/brake/gas crowd. My last tank is an anomaly in that I'm trying some different fill techniques to see if my range is extended enough to be worth the effort, otherwise that tank would have been in the 52 MPG range.

But, I'm not an atypical driver. I bought this car with every intention of wringing each and every MPG that I can from it. I travel about 30k miles per year, and have done so over the last 3 years. With my Elantra, at 37 MPG at 811 gallons at 2.50/gal that's $2027/year. And that was truly hard fought, especially when my wife started driving it more often. With this car, provided I can average it up to 55 (currently at 52.1) MPG, that cost is $1363/year at 545 gallons.

But, what if gas sticks at 3-3.50/gal? That Elantra costs me $2838/year on the high end. The Prius costs $1907/gal.

So, I guess it depends on what your goals are... for me, it's mostly about future proofing how much my gas bill is going to rise. I needed to replace the Elantra anyway. It's a 10 year old car from the North East, and things like the exhaust are starting to just rust away. It's also going to need struts on all four corners ($500-1000?), another timing belt, replace the accessory belts, ($500) fix the rear window power motor ($238 in just parts), fix the other two that have not broken yet but will, probably another coil pack($200), etc. Basically, it's getting to the point in its life where Crap Just Breaks (tm).

Is $600-$800 in gas savings worth it to me? Yep. Does it cost me time? Yep. Does that bother me? Nope. I have a much safer car, a newer car, and if I really push it, a car that can average (me) 60 MPG. But again, I'm not an atypical driver .

 

Too many words to read them all... But I'm starting to think there's a more substantial hit going from 35F to 25F than from 70F to 40F.

Any guesses why the line would become a cliff around there? And does it level off at some point?

 

My guesses?

• Colder air is denser. No change in speed on your part, means you're fighting greater friction at lower temps.... though, is this going to be measurable? Probably, if you have the time, money and inclination.
• HV battery. Colder temps for some reason force the Prius into a more aggressive battery maintenance mode. This means more fuel is wasted to maintain the HV battery. I've noticed that I spend more time at 7 bars in cooler temps on the highway, than at warmer temps.
• Heater. There's not much waste heat to begin with, running the heat forces the engine into less efficient modes. I keep my heat at the lowest fan speed, and about 68 F.
• Higher rolling resistance for your tires... heck, more friction for fluids starting out as well.
• Warmup takes longer, leaving you in an inefficient state longer starting out.
• Letting the car warm up to de-ice, etc.

K... I'm done rambling for now .

 

I think that covers it pretty darn well. Perhaps add greater air resistance from dirty/ice/snow car (surfaces).

 

I'm not as sure about the air density thing (since you might expect similar gains at higher temps - no "cliff"), or even the heater (assuming you don't blast it), but I definitely agree about suspecting the tires - in really cold temps at high speeds, maybe they're never completely warming up and reaching optimum flex for lowest rolling resistance. And that would be most significant at highway speeds.

And I'd really like to know what is happening with the HV battery - one major difference yesterday was that the cabin was actually so warm (from the sun) that I turned on the blower to get COOL air... If the ICE is spending more energy on battery maintenance, that could be a significant parasite.