Colder weather has zapped my mileage to 44mpg

3 times now.

The engine-light came on in my mom's car today. I plugged in the ScanGauge and immediately knew the nature of the problem from the code revealed. In this case, it was P0133.
.

 

I think your first statement is a stretch. New EPA mileage figures felt that there was a shortfall on vs. (old method) EPA figures on 90% of the vehicles. With the new method, they figures are closer but they didn't quantify how many are off now. But, CR's tests aren't anything like the EPA's tests.

While digging for some posts, you mind find ZVW30 figures from charts at http://priuschat.com/forums/gen-iii-2010-prius-main-forum/66018-looking-speed-vs-mpg-graph.html and http://priuschat.com/forums/prius-hybrid-news/68731-consumer-reports-mph-vs-mpg.html interesting as well as Consumer Reports Cars Blog: Tested: Speed vs fuel economy (too bad no Prius is in there).

Since you mentioned Honda, while searching for an old post on speedometer and odometer accuracy, I found the article I linked to before: Speedometer Scandal! - Feature - Auto Reviews - Car and Driver. You might find the PDF at http://www.caranddriver.com/var/ezf...lication/1e1b33f85f31df61e4830f32f82a5a71.pdf interesting. I then happened to stumble across a Honda class action lawsuit settlement (I posted about it at http://priuschat.com/forums/other-cars/28867-honda-settles-suit-over-defective-odometers.html >2.5 years ago). See below for non-expired content:
Honda's miles whizzed by too fast - Los Angeles Times
Automotive Digest: Honda Settles Class-Action Suit on Speedy Odometers

I did some hypothetical calculations based on your reported Honda numbers (and assuming a 2.5% odometer inaccuracy) and found that for say a "410 mile" tank, you could be off almost 1 mpg due to rounding. Example:
"410 miles" / "28 mpg" = 14.642 gallons
400 actual miles / 14.642 gallons = 27.31 mpg (or 27 mpg, if you round down)

If the error were 4%, then the actual mpg could be 26.92 mpg (round up to 27 mpg). However, this isn't enough to account for your reported Honda mileage vs. EPA figures.

 

I must say that since I got my prius a little over two weeks ago, we've had very cold weather in Chicago and I'm still averaging out 49 mpg, before I installed the 3/4 inch pipe insulation ($2.14) this weekend. Driving it to work today to see if the mpg increases as a result of the grill blocking. Last thing left is for Wayne to install the EBH and the 25 mpg average for the first 5 minutes of driving should be fixed. If I can average out the advertised mpg during winters in Chicago, I don't see why you can't. Maybe you should take a look at your driving style. This site is a great tool to use for development of prius driving skills. Thanks everyone for all of your helpful advice.

 

It is wimpy when you know your best tank MPG in the summer was 64MPG!

BTW, my MPG in my last trip, under 10-12F, was 40 indicated, more likely 37-38 real. Pretty pathetic...

 

I'm so glad you mentioned trip computer inaccuracy. I do not have one in my Odyssey but my calculations in my previous 07 CR-V revealed that the indicated MPG was incredibly accurate, usually around 0.5 MPG bellow calculated.

The 2010 Prius trip computer, though, is remarkably inaccurate. The difference between indicated and calculated MPG is always at least 2 MPG bellow and often more than 3! Some user of this forum said once that there is an article somewhere implying that Toyota overestimated the indicated MPG on purpose. And it is not only the MPG that is inaccurate, my GPS unit also taught me that the average speed is also underestimated.

 

Hi there, nothing in my driving style thas changed from summer to winter... I'm talking about hwy driving, there is not much to change besides speed, but I have kept the same style, same tire pressures, same average speeds, same cargo load, but different temperatures... the colder the higher the MPG hit... the hit could be anything from 20 to 35%!

 

Cold Snap last two weeks. Worst ever MPG so far- 41 Actual at the pump. (44 indicated on the readout).
This is rediculous!
Hope it doesn't get wosre!!!

 

there are literally dozens of threads going around that are pretty much similar in themes, most concerning gas mileage...after all, that is one of the main themes about owning a Prius, so understanding is a key thing when things dont happen as you expect them to. below is a post that i put in the fuel gauge inaccuracy post that does apply somewhat here.

now; in this thread we have people who are getting crap mileage, some getting ok mileage and others who havent a clue as to what we are talking about because they are getting great mileage.

i think what we have to realize is that mileage is relative. its no different than the ability of a person 7'2" who can dunk without really trying verses someone 6' 2" who has to give it his all.

in some areas, its a real accomplishment to get 45 mpg. in other areas, not getting 50 mpg means you are simply not trying. so when we post that "i do this and that and get 55 mpg" well that is great, but dont expect that to really allow anyone else to do that and get the same results.

there is really a small set of guidelines to insure that you are getting the mileage you are "allowed" to get based on your driving situations. so one thing to keep in mind; it only takes a second to post your location and really makes all the difference since we can easily see a 15-20 mpg difference here and most of that is NOT attributed to driver skills.

http://priuschat.com/forums/gen-iii...oyota-prius-fcd-inaccuracy-7.html#post1021383

 

Good point. Location, size, and nature of commute, type of terrain, etc all influences your MPG hit; however, if people just say how much the MPG hit is right now compared to what it used to be, that single piece of information carries the most value because you are comparing summer and winter MPG in the same situations.

My lifetime calculated MPG is standing right at 48 MPG now, a 10 MPG drop in just less than 2 months and going down... by the end of winter I suspect it will be around 40-42 or less, unless the grill blocking helps, which is questionable given my 99% hwy driving.

 

I'm not talking about the trip computer (or lack of) on your Hondas. I'm talking about the inaccuracy of their odometers. You may have actually traveled less than what the odometer indicates, leading to inflated mpg figures. The class action suit went by the odometer being 2.5% too high.

 

Sorry, my response was incomplete... I was in a hurry... The odometer in my CR-V was sharply accurate by comparing to my portable GPS data... so, the MPG was indeed very accurate in my CR-V...

Last time I heard Toyota customer service was going to release an official note about how tremendously overestimated the indicated MPG is in the 2010 Prius, but haven’t heard ever since...

 

daveinolywa has the correct view, http://priuschat.com/forums/gen-iii-2010-prius-fuel-economy/73008-colder-weather-has-zapped-my-mileage-44mpg-19.html#post1021406
when I first started I had hoped for 60+mpg however based on my personal daily commute and 18 months worth of driving, I can only hope for 45+.
Winter driving does affect mpgs but in my case thus far I am only down 4-6mpgs per tank.
Changes in temp, road conditions, traffic patterns (some drivers more cautious), gasoline blend, and many other factors change the optimal performance of all vehicles. Take all required steps to improve your winter driving mileage.
Elite athletes take a hit in their optimal performance when conditions are off ie: lack of sleep, partying, marital distractions, injury, etc. The sports fans notice as our expectations are high for them to out-perform and 'we' notice the difference in their game, stats and possibly their teams overall performance.
However, my personal 'game' (as a non-elite athlete) does not vary drastically depending on my party habits, injuries or other distractions. My game does not 'suck' all the time, but I am also not being scouted by a professional team either.
We could look at the Prius as an elite athlete that has peaks and valleys in performance but we know that during the playoffs, the game will come back and all the past poor performances will be forgotten for another season.
Every other vehicle on the road is an 'arm-chair' wanna-be that is mediocre at best with the occasional foray into the big league only to drop by the wayside and be soon forgotten.

 

Hum. I’ll have to assume you are serious here.

To make an analogy: its like recruiting Lance Armstrong to act as your personal courier carrier, expecting him to always ride at 40km/h and complaining that his average speed drops to 25km/h when you put him on ice and in adverse winter conditions, while the average John Doe courier goes at 15km/h all year round.

The EPA tests were not made for efficient cars. They were made for inefficient non optimized cars and assume their FE will be almost the same in very different conditions (a mostly correct assumption for a non hybrid car). The Prius pushes optimizations in many aspects (Atkinson engine kept most of the time at its peak efficiency, aerodynamics, regenerative breaking, just to name a few, etc.). This, of course, means that having adverse conditions to those aspects will have a greater effect on FE than on a non optimized car.

If your point is in getting the most accurate EPA rating, please buy a farm tractor. I would bet that its EPA rating accuracy would by pretty darn accurate!

You also have to understand that the car was not optimized to run at 130km/h, at which speed the engine is probably forced out of its peak efficiency.

If you find a car that objectively offers better FE in your specific driving conditions, please name it, buy it and sell your Prius. Otherwise, I’ll join the others in not understanding what your point is.

For one, all I have to say to Toyota is thank you for still improving FE in cold winter conditions, compared to the last generation.

 

Quite frankly, I’m near to give up... I don't know how many times I have to explain what my point with the Prius FE is... I thought I made myself clear but clearly there are some people who still don't get it. Maybe, it is because some has not followed the whole history... or maybe I wasn't as clear as I thought...

Anyway, here we go again:

I have 2 cars right now... and I used to have a CR-V, which was replaced by my Prius.

I tend to drive my Prius a lot more careful to optimize FE compared to how I drive my current Odyssey and drove CR-V. Yet, here are the numbers of my average hwy summer and winter MPG respectively:

Odyssey: 26/25
CR-V: 29/27
Prius: 58/42 and winter number keeps going downhill... will soon hit <40

There is no question that the Prius, even with the ridiculous winter hit (I'm not the only one with that conclusion here but folks like to pick on me), is more FE in the hwy during winter compared to my Odyssey and CR-V. BETTER BE, THAT'S PRIUS MAJOR SELLING POINT!

What I'm questioning (and I'm sure you can see it) is that the percentage hit in the Prius during winter is outrageous compared to my other cars.

Forget about speed, driving habits, energy loss theories, and all other excuses folks are coming up with… I’m not looking for excuses! Fact is all those 3 cars above were submitted to the same or similar driving conditions!

Now, I'm not trading in my Prius... As much as I think it somewhat fails to deliver what it is supposed too... I keep a car until the wheels fall off like Bob Wilson like to say...

That does not mean I should turn my back to its failures and praise it like a little machine miracle... far... VERY far from that...

 

Indy,

Did the Odyssey and CR-V get MPG 20% better than EPA figure in the summer?

 

In the hwy, both the Odyssey and CR-V were definitively 20% or better than EPA... In the city, if I recall correctly, it was above EPA but the difference was lower.

I never really paid attention to EPA until I got the Prius… the estimates for my CR-V and Odyssey were highly underestimated…

 

INDYKING,

I am with you; figures don't lie. Our Prius is also taking a big hit on MPG's. Our other car, a 2003 Jetta wagon (diesel) TDI 5-speed manual, only loses about 1-3 MPG's in the winter and current average for nearly 130,000 miles is 53 MPG.

Why is it that I do not see a big drop in the diesel MPG's but yet the last fill up for the Prius was 42 MPG's, from a September high of 57 MPG's. Also Oregon is a 10% Ethanol state ALL YEAR LONG.

Yes and the 2003 Jetta TDI is rater lower EPA, than the 2010 Prius, based on the 2008 new configuration for MPG's.

alfon

 

Thanks ALFON!!!! I was looking forward to find out how severe winter affects TDI MPG... Since I drive mostly hwy, it seems that if I got the Jetta TDI instead of the Prius my overall yearlong MPG would be better in the Jetta TDI than in the Prius... maybe?

 

Seriously? I don't see how getting 40MPG instead of 28MPG is costing you more.

I can see how you're upset the magical engine fairies don't work during winter, but seriously, if you average 58 for the summer months, and 40 for the winter months, you're still going to average out at the EPA 48MPG. You're getting exactly what was advertised.

Are you upset that you might not get significantly better than the EPA estimation? Did you make your cost/benefit calculation on the EPA estimates, or on your super unrealistic expectation that you could maintain 58MPG indefinately?

What you don't seem to understand is that a hybrid is not a normal car and will not behave the same as a normal car. The fact that the engine turns off while coasting means that it will cool down fast in cold conditions and need to turn on again, which will make it's fuel efficiency, which is based on how much the engine can be turned off, suffer. you don't see that in a normal car because their engine never turns off, and their fuel efficiency sucks all the time.

Also, how did you calculate your cost/benefit? I'm not sure of your math, since I could buy a Hyundai Elantra for $15K and get a reasonable 35MPG highway with it. It would take 430000 miles of driving at $3 a gallon before you broke even with the extra $10K it costs to buy the Prius. Almost half a million miles.

The Smart Fortwo, for $13K, gets an EPA estimated 43MPG, and you would have to drive 1.5 million miles in the Prius before you paid off the extra $12K it cost.

If your only consideration was financial, you bought the wrong car.

(Edit) Oh, and, you would have to drive 560K miles in the Prius to justify buying it over just continuing to use your CR-V.

 

Buyer's remorse seems to be the theme now, since all the complaining hasn't actually achieved anything... yet it continues.

Countless supporters here bend over backward to assist with the purchase research. We want to prevent this very sistuation by providing lots of real-world info. And we've been doing it for 9 years.

How can 44-winter / 50-annual be considered disappointing unless it was financially based?
.