Colder weather has zapped my mileage to 44mpg

I'm starting to wish I had a Scanguage, because I think there are 3 different efficiency "levels" related to engine temps ("cold" being L1). I say this because when doing short trips, the efficiency seems to bump up a bit after 5-10 miles, but then there's another bump somewhere after 15-20 miles (roughly - haven't nailed it down yet). Grille blocking seems to shorten those distances by a few miles.

With a 360-mile highway trip, I would be interested to see what the baseline (warm-weather) mpg was... If that was lower than most drivers get in warm temps (and most drivers seem to be getting well over 50 in those conditions), then it would make sense to see the same thing (below-average) in cold temps also. Which would point to it being a problem with your Prius (rather than with ALL Priuses). Unfortunately, proving that to a dealer would be next to impossible unless you have friends in the EPA who could put your car on their dynometer to run the official tests.

 

25% loss due to cold weather seems very normal to me, and that is solely from non-hybrid experiences, as my Prius has not seen warm weather yet.

 

Excellent points! I started my trips when the weather started cooling down so I don’t really have a summer trip yet. My warmest air temp trip so far was also my first one under dry conditions and 64F... MPG was 55 (MID) but only 51.2 calculated. Detail: the MPH for that trip was 55 MPH, so about 12-13 bellow my average.

I'm getting ready for my first trip with the block. We’ll see what happens. I’m excited.

Also I noticed one odd thing in some of my trips. It is not uncommon to see a prolonged drop in the MPG after about 1.5-2 hours driving steady on cruise control in the same speed, same temperature, and flat way. I have no idea why that happens?!?

 

No doubt wind is going to be a yes/no variable too, in this one of a kind study that Toyota just cannot wait to receive.

 

What happened to these mpg's that you posted back on #98?

You are the only person on this site that I have seen that has come anywhere near 58 mpg at 75+ mph. Care to explain how you accomplished this feat?

 

That's unusual - how much of a drop are you seeing, and does it stay there for the rest of your trip?

 

I discovered why my MPGs has been low after the last snow storm. It turned out the under-body cover (under the front bumper) was hanging down, scooping in extra air into the engine compartment. It was just the driver's side, probably from the snow rubbing under the car. I fixed it and the MPGs are back to normal.

Lesson is to look under the car to check visually.

 

That particular claim is a wild one. Even at the peak of summer, I haven't seen that at such a fast speed.

The detail repeatedly promised is where?

If all we get is continued complaints without getting to see data, this thread is dead. Of course, I did ask what was hoped to achieve earlier and got nothing in response.
.

 

You're not doing bad for who was not supposed to post in this thread anymore... but you're not paying much attention. Like I said before, I don't really care if Toyota pays attention or not to my data. I'm also not going to post it here because even the best study in the world can't change some people's mind. I will send it privately to whoever is interested here and will honestly be more than glad to do so. It was my dealer manager who convinced me to run the stats and send it to TMC when I told him about my data a couple of months ago.

Again, the 2 and only reasons for my study:

1- I love collect and evaluate data.
2- My curiosity for what is really going on (whether or not it changes anything already known) is the only reason why I still keep my Prius.

 

Yea, I know. Frustrating....

 

I'm sorry... I was talking about my cruising speed for the most part on those particular trips... the average MPH was actually around 66-67...

 

I'm still doubtful.
Our observations are...
62 mph average speed: 58 mpg at best
67 mph average speed: 55 mpg at best

Ken@Japan

 

COOL! I love a challenge... When summer comes, if I have my Prius, I will do it, take a photo of the MID, and send it to you with much pleasure and satisfaction! I have done it more than once and I will do it again...

 

Filled up the other day after a 280 mile round trip to Cabelas in Lacey, Washington, plus another 40 miles or so of around the area driving etc.

MPG calculated was 47 MPG, I don't know what the exact MFD screen read because my wife filled up and she is not into MPG'S. She did tell me she believed it was 50 mpg or so.

Now in the summer the MPG would be around 55 MPG for the trip, this is calculated not MFD read.

Yes, winter does take its toll on MPG's more than any other car I have had in my entire life and I have been driving since 1960.

Note: The Prius tires are the best fuel economy tires you can buy, Michelin Energy Saver Tires, 195X15X65, filled up to the max, 44 PSI nitrogen in all four tires. Tires now have 6,000 miles and are fully broken in.

Also the oil is Mobil One 0X20 Synthetic with 4 quarts in the crankcase so it is not overfilled.

As you can see everything is set up for Max. MPG's.

But, it still did not break the EPA of 48 MPG highway.

My 2003 5-speed manual TDI Jetta station wagon, always exceeds EPA even in the dead of winter, about 52-53 MPG average.

alfon

 

A big help for gas mileage in the winter is actually lowering the cabin temperature. I live in Northeast Ohio and even with letting it idle while I brush off the snow I can squeeze 48 MPG out of most tanks. The lowest I ever had however was a week where we never reached double digit temperatures for about a week straight last year and it dropped to 36 MPG.

 

Then why are you posting anything here?
.

 

Prius mileage is just plain weird. When the temperature dropped a few weeks ago I went from 47 down to 43. A week ago I filled up at a little independant station called Skywood Trading Post in Woodside, CA. Drove down to La Honda, then uphill most of the way to King's Mountain. Strangely, the displayed mileage was 54 even though most of it was uphill. Later in the week I drove along the coast to Pacifica (lots of rises and drops) and over the mountains separating the Penisula from the coast several times. Over the last 370 miles I averaged 49.7 based on fill-up and 51.9 based on the comp - my best numbers ever by both calculations. Lots of hills, lots of highway. I have no explanation for it unless there was something "different" about that Skywood gas.

 

Keep an eye on your average speed too. For me that makes a fairly large difference too. Could be on that trip your average speed was much less than you normally drive.

 

Indyking, I just don't understand why you are trying so hard to prove something that was proven years ago? If you love to research and collect data, why did you never read the Gen II threads dedicated to this topic before you bought your Prius? Also, your heavy bias against the car makes it difficult for anyone to take the results you post as an honest study! Kind of like when the oil industry presents their "data" on climate change...

 

there is nothing wrong with data collection and since all driving conditions are different, YMMV!! so knowing exactly what to expect only gives one a heads up as to possilbe problems when the mileage is not waht is expected.