Well wont be too long till winter comes .I would like to know at what temp you start to feel that the mileage starts to decline? Also how much of a dip do you see in the middle of winter.You prius owners in flordia and some other southern states may be lucky not to see any mpg loss in the winter .
Really depends how sensitive you are to mpg changes. I can tell when temps drop to 70 degrees, no issues, really, b/w 70 and 100 though I do get a little better mpg in the low 80s only b/c I can usually get away w/ not using AC. I think the thing that makes the biggest difference is the cold starts on days where the temp is below ~40...esp. if your car has had a good "cold soak" outside or in a non-heated garage. Your ICE is colder and the battery is colder and it takes longer to warm everything up b/c it's cold air outside.
last week or the week before when we had rain, it was only 12°C and the mileage took a hit. Where it usually would've shut down at the first traffic light during the summer, it'll run during the winter and it ran that week it rained.
the biggest hit comes from "winter fuel" and you should start to see the effects of it soon. Use a block heater on a timer if you car is outside or in an unheated garage. I'm not sure what your winter temps are like but here it's like Seattle Washington, near freezing for a couple of months and soaking wet which helps pull what little heat the ambient could provide us with. If I had to guess the amount of "hit" that I take I'd say probably 3mpg US. No snow to speak of but rain for weeks on end last winter but the winter lips and full time use of the block heater for 4 1/2 hours per night made a difference from the first winter which wasn't a full season as I bought the car in March.
<div class='quotetop'>QUOTE(stanlwyjohn @ Oct 2 2006, 11:00 AM) [snapback]326667[/snapback]</div> This guy feels every degree. Following chart is his mileage vs temp record between May and September. The horizontal axis is degree C and the vertical axis is km/L. The pink plot is last year without using an engine block heater and the blue plot is this year with EBH. Ken@Japan
<div class='quotetop'>QUOTE(efusco @ Oct 1 2006, 09:54 PM) [snapback]326697[/snapback]</div> So basically you're saying since colder weather may cause the ICE to run more that will impact MPG? Related question... how does the Pirus handle in heavy snow and ice. Live in the Chicago area, we haven't a real Chicago winter for awhile, but you never know when the next one comes along.
I have shown my chart to many people and most are truly surprised with the tracking of mileage to temperature. This year has been an interesting one since for the last couple tanks the average temp has decreased but I was still getting really good mileage. I take that to mean that I'm finally figuring out how to drive this thing! Anyway, click the "Current Mileage" link in my signature to see my chart.
My first sub 50 mpg tank came a few weeks ago when it was chilly (low 50s) and raining in Seattle. It's warmed up since then and I pulled a 50.9 tank despite a long trip going 70 over mountain passes yesterday. So far at least, the sunny/raining thing seems to make a bigger difference than a few degrees.
Great chart tony Do you use snow tires in the winter?im guessing i might get an additional mpg hit when i get mine.
I don't notice a lot of difference between Summer and Winter MPGs. Seems the 100+ temps in the Summer runs the AC more, and the lower temps in the Winter runs the ICE more for heat. Consistently, the best MPGs I realize are in the mild days - Fall and Spring. In any event, I do appreciate the much lower per mile cost for fuel. For over two years, I have averaged 5.61 cents per mile for fuel.
<div class='quotetop'>QUOTE(stanlwyjohn @ Oct 2 2006, 02:28 PM) [snapback]327029[/snapback]</div> Thanks. No, I do not use snow tires.
<div class='quotetop'>QUOTE(ken1784 @ Oct 1 2006, 08:26 PM) [snapback]326709[/snapback]</div> interesting showing both non-bh an with bh his results are a bit better than mine I'm seeing about 3MPG imperial and he's doing 5 MPG imperial better using a block heater. Thanks Ken for posting this chart.
<div class='quotetop'>QUOTE(ken1784 @ Oct 1 2006, 11:26 PM) [snapback]326709[/snapback]</div> I never imagined using a block heater at these temps before. Between 66 and 91 degrees Fahrenheit? Looked at another way it seems using a block heater improved his mpg as much as 10 degrees Fahrenheit warmer ambient weather. Do you know what his driving patterns, average trip length, were? If I recall, they don't get the coolant thermos in Europe; does the Japanese domestic market Prius include the coolant thermos? Has anyone done any estimates or back of the envelope calculations comparing total energy costs of driving their Prius with and without an engine block heater, in terms of money or CO2 (from generating additional electricity for the open market)?
As the temperatures have been dropping here, I have noticed my mileage going UP. Basically less A/C use.
Must be a Floridian thing lol. My Prius was blowing the heater this morning (set at 22.5). On the way home, it's blowing the A/C (OAT rose from 10 this morning to 15°C)
<div class='quotetop'>QUOTE(theorist @ Oct 5 2006, 02:43 AM) [snapback]327948[/snapback]</div> The EBH helps mileage numbers even in summer, especially for short trips. His data is about 20 miles one way commuting. His road is two or three lanes and speed is below 42 mph barrier, avg about 30 mph. Edit: Frank is correct. Japanese Prius doesn't have the thermos. He used the 400W EBH for about two hours every morning. In Japan, the electric fee is expensive and he lost the total energy cost. Ken@Japan
<div class='quotetop'>QUOTE(theorist @ Oct 4 2006, 10:43 AM) [snapback]327948[/snapback]</div> I'll be doing another post on the cost of the block heater operation for a 1 month total, in about another 6 days I'll have logged the cost. I run it on a timer for 4 1/2 hours a day for the day's I commute and so far in 24 days it's cost me $2.51 I work 4 day weeks and it's on an 03 without the thermos. I used to only run it in the winter but this year I've used it in the summer as well. Like I said it raised my mileage approx. 3 miles to the gallon (Imperial) Our gas costs as of today 97.9 a liter Approx $3.21 a US gallon. All our electricity is Hydro Electric Power. Edit: the JDM Prius doesn't have the thermos. Edit 2: the calculation on the watts of the Toyoat block heater is 378 watts for 65 hours of operation according to the WattsUp Pro meter I'm using.
My data tracks close to Tony's. Mileage drops in winter due to longer ICE running to warm up. Mileage drops again when it gets really hot and A/C runs all the time.
