Colder weather has zapped my mileage to 44mpg

I’ve got only 2 trips using scangauge recorded so far. 31F and 11F outside temperatures, cruising at 65-75MPH, water temp stayed always above 190F after initial warm-up, often 193 or 195 but occasionally hitting 197 or 199!.

 

The Prius should most definitively have winter and summer EPA ratings...

 

Just did 2nd fill up on our new 2010. First tank 47.3 mpg. 2nd tank 41.7 mpg. (MID 5% higher than these) Both have lots of short trips and cold starts, lots of snowy streets, frigid temps, and in the 2nd tank the one highway segment (150 mi) was into a 25 mph headwind at 65-70 mph.

These are without using the SG yet, and much of it with my wife driving after which I tend to find the defroster on, etc.

I expect a 3rd fill Thursday, then plan to block the grill before a highway trip where I hope to average 55 mpg in frigid cold (10-15 F) temps.

These are fantastic results to me. Slow down. Air up tires. Block lower grill. Use a SG. Apply some techniques like P&G, DWL, etc.

Yes, some choose to drive 75+ mph, etc., and get a lesser % of EPA than those choices produce in non-hybrid cars. The thing is, it is just as easy to deviate the other way from EPA conditions and get 60, 80, 90 mpg. What non-hybrid allows that? Prius 2010 allows a nearly linear mpg choice at steady speeds between 20 and 80+ mph. Anything that deviates from ideal (slush, cold, warm-ups, stop & go, braking, climbing, headwind, etc) requires more energy to overcome. It is well known that high speed driving is not the strength of the Prius. Yet even there it competes pretty well. John1701a's 8 or 9 years of data show the nice FE improvements with each generation.

As much as I love the Prius, if I drove all highway at high speeds like the OP, I would look hard at a 5 speed (TDI, econobox). Perhaps he can trade with a TDI owner who no longer drives highway. A high constant demand for power is not what hybrids are best at.

As for me, I have changed my driving habits to exploit this tool, and have never arrived so relaxed at my destination.

Best of luck.

 

Remember, Prius is a slave to emissions control, so a higher normal temp is likely by design.

 

Hwy-only MPG in my Odyssey has dropped from 25/26 to 24/25 in my last trips during the past winter... i.e. less than 5%...

 

You do realize that the person who posted the OP is not me (Indyking), don't you?

Indyking is not the OP of this thread... I know some of you are under a false impression here... go back to the OP in the first page and read it…

But since you touched it... if I find a 2010 A3 TDI owner who is willing to trade... I would not hesitate a second... but not interested in a VW TDI because, unfortunately, as much as my Prius is delivering way bellow my expectations in comfort (the seat support problem), interior quality (rattles and creaks), and FE (winter issue)... it is supposed to be reliable with low maintenance costs since it is a Toyota, although it's too early to tell... I did lost a front wheel cover in my last trip out of nothing and the flying cover could have caused an accident... no pothole, no flying stone, or any object hit my wheel and my wife swear she did not hit a curb or anything when she drove it the day before my trip... the cover just detached and went airborne...

 

Had forgotten that. My bad.

 

My data so far is showing pretty well that air temperature rather than speed is the Prius first enemy... not that speed does not have any influence because it does a lot as you know...

My average MPH for my long trips is often 66-68... I usually cruise at 65-75 MPH... keep in mind that for 60% of the time the speed limit is actually 70MPH, 30% 65 MPH, and only 10% 55 or bellow...

So, the impression that I car race is wrong too...

In fact, where I drive, I find myself being passed more often than passing others...

 

Maybe you and BobWilson4Web can set up some tests on air temp impact at select speeds over a fixed course.

I have no problem with your chosen speeds. If in a hurry, I would pass you, but don't hold your breath on that happening.

You should observe close to 60 impg at 60 mph in warm weather. With grill blocking, maybe 55 impg, just guessing.

 

I drive at night for 360 miles each trip.... so, cruising at 60 MPH would bring my whole-trip average MPH to around 56-58, which is a 10 MPH drop from what I do right now... my trips would take 6.5 hours instead of 5.5 hours... 1 extra hour is a lot at night under sub-freezing temps... so much for improvement in FE... trust me.

 

Yeah, but you can observe your 1 and 5 minute bars for a while at 60 or 50 or 90 or whatever, so you know your choices.

 

Yep, agree. It’s a personal choice for some, but it is a safety issue for me more than anything. Driving after 11PM or close to midnight gets out of my comfort zone, where I start feeling tired and it is aggravated during winters... so, speeding up keep me arriving early and alert all the time. It's not like I'm car racing... I could go faster and still feel safe... In fact, I never got any speed and/or any traffic ticket for that matter... true, I do have a passport 9500ix that help me to keep clean…

 

When I first got my car in August, I did record some short trips on the Trip B display. The best 52 mile round trip to work, with 40 miles at 60 mph highway speeds in cruise control and the rest stop and go city traffic, was about 53.5 mpg with the temps in the 50-80F range.

After reading all these posts on how cold weather zaps mileage, I did another short trip today. The temp this morning was 23F and the return trip tonight was 36F. My mpg - 54.5 mpg !!

My only explanation for this is the improvement in FE with the car breaking in exceeded the loss of FE from cold weather. If someone can give me a better explanation, please do.

On the other hand, while I was on vacation during the holidays and doing all stop and go driving in the city and with short trips, my mpg dropped to about 39 mpg.

So, from my experience, yes the cold weather impacts the mpg on short trips but very little on longer trips when the engine is warmed up.

 

For me, today, it was 54.3 MPG at 25 F over 6 miles to the kids preschool, then 54.0 over 51 miles to work at 25-27 F. Then 63.1 over 41 miles to the grocery store, and 70.8 over 6 miles to the house at 36 F.

A few things to note:
* I let the heat sit at 68-71 F. I set the fan speed to low.
* My tires are at least 44 PSI
* I don't travel over 60-65 MPH.
* NC is pretty darn flat on the eastern side of the state.

 

CHeck the tire pressure. Drive in ECO as much as possible. I use PWR only when necessary and our temps have been running in the teens these past weeks. I am doing well.. 49 to 54. I think the cold starts have a big play on this too. Other owners in this area tell me about 5 mpg less in the winter. I am happy with what I am getting. My TDI gets 36 to 38. At $286.9 per gal is not a bargain..

 

ECO mode is useless if you’re driving in the hwy and may help a little with city driving if you don’t know how it works. The only time it really helps is in the summer to keep the A/C output optimized for FE. Remembers... it only changes the sensitivity of the gas pedal... engine power is the same for all modes...

 

Good numbers but you are getting no more than I would expect in such high temperatures (yes, where I drive, your temps are almost spring like for this time of the year) and such low speeds.

 

It also helps a lot during the winter.

Also changes the way the heater works: which vent, fan speed, (re-)circulation modes. In cold climate, it will also affect when the ICE triggers just to make heat.

It is especially useful when you know how it works.

 

The person who I was responding to implied that he/she uses the manual heater set on low heat... I'm pretty sure ECO has no impact on the manual heater... it mat have in the auto heater but I don't use the auto because I found it hopeless since it blows cold air instead of actual hot air unless it is bitter cold outside...

I have tested many times ECO vs. NORMAL vs. PWR mode cruising steady in the hwy with manual heater on and I guarantee you there is no noticeable difference in FE…

I don’t think it is your case but many Prius owners think ECO saves gas but it is a common misconception because it does not, it just change how much pressure you have to apply to the accelerator to get it going and changes the auto climate outputs…

 

95 mile almost all highways trip yesterday along with a drop in elevation of about 1000 feet in mid 30's F temps, 6000 feet altitude, good quality, dry roads. I avoided rpm over 2800, and max speed was 64 mph but average closer to 60 mph. The few places I could check, no significant wind

SG: 60.7 mpg

Not too shabby for my top grill blocked G2 Prius. For comparison, I see 61 - 63 mpg in the summertime.