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Discussion Starter #1
I'm finding that since it's gotten cold, I lose MPG very quickly. I have a short commute, rarely able to go faster than 40mph (a 6 mile drive that takes 20 minutes). I'm having trouble getting out of the mid 30s (MPG). Even after 20 miles, I'll lose an .1 or .2 MPG before I get to the end of the street.

My tires are at 40/38, as suggested here, I feather as I drive (I've been told I now drive like I'm 90 years old), but when it's 15 degrees out, I HAVE to use the heat, and probably the defrost!!

Any suggestions? (besides get a job that involves driving on the Parkway or moving to Florida)

thanks
 

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Florida is good but further south is better. Welcome to the club. Don't in any case turn on the front window defroster. I roll down the side window and stick my head out. The defoster is a killer. :shock: Really all the heat comes from the ICE and we in the North Lands take this hit. Just imagine how bad it was with your previous car!
 

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I understand completely, drtravel. My last tank was 29. Heat, both rear and front defrost, 3 mile trips, warming car, it's just awful. I bought my car last March when winter was dying down and the weather becoming springlike. This has been an unusual December here in the Midwest so far. We've had nearly 3 straight weeks of snow, wind, cold---horrendous mpg. I've already decided not to worry about it until warmth returns.
 

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Discussion Starter #4
i agree

i also bought my car in late March and rarely used the heat. But this fall lin NJ has been extremely cold. The MPG shoots up when I get on a highway, but, like you, I drively locally (and slowly!) most days.

I guess there's no point in heating up the ICE before I drive.

Happy Holidays to all!

David
 

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A lot of the mpg loss is just the ICE taking longer to warm up in cold weather. Since the heater is also on, it gets blamed. Even with minimal heater use, I'm noticing that the Prius takes 15 full minutes to warm up when the temperature is below 20.

This is my first full winter with the Prius, but so far my impression is that increased ICE warm-up time is THE major factor in decreased winter mileage. Two days ago, we drove to Denver and back - 150 miles- with temperatures mostly in the 'teens; the mileage was only down about 10 percent from summer. But the short hops around town are WAY down from a couple of months ago. Our tank mileage now decreases on trips where it routinely increased back in September.
 

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as a prospective buyer . . .

I have another question: how well does the heater work? I'm willing to lose mpg, but not for a heater that's ineffective.
 

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The heater works well, but warmth comes only when I'm about to reach my destination 10 to 15 minutes away--unless I warm up the car first. The biggest jolt to me wasn't the 29.1 mpg, but that with 3 pips left on the fuel gauge, I'd only accumulated 160 miles on this past tank!
 

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iggy1iggy said:
one reason you may be having this problem is if you are using the windshield defroster the AC compressor is running also to dehumidify the air blowing on the windshield.
Wouldn't the MFD climate screen show AC on if that were the case?
 

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Re: as a prospective buyer . . .

sjerseycraig said:
I have another question: how well does the heater work? I'm willing to lose mpg, but not for a heater that's ineffective.
The heater works as well or better than other vehicles I have owned. I have had mostly Ford vehicles and their heaters are well known for being very effective and I would easily say this heater is as effective or more so than the for Fords I have owned.

Plenty of posts out there about how this car retains engine heat using a coolant storage container. I'll find the link and post here. There is a thread with a good picture of the system that was pulled from Toyota's official hybrid newsletter.

http://www.priusonline.com/viewtopic.php?t=6479

The retention of engine heat in the hot coolant storage tank does help to bring the entire system, ICE, cats and cabin up to temperature faster than if the car was being brought up to temperature on its own. The auto climate system governs the ICE during the winter and will run it to provide heat to the cabin even when the ICE should be off, say at a stop light or when coasting down a hill.

My test for how well a car heats the cabin is pretty simple. When I was sill in college I used to make a number of trips home for holidays and weekends. These were 200+ mile journeys. Nothing worse than driving for 200 miles in a heavy goose down jacket, let alone a lightweight windbreaker. I always preferred to drive during the winter in shirtsleeves. So, if a car, during the dead of winter can keep you warm in your shirtsleeves the heater works just fine. The Prius does this very well.
 

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evander said:
iggy1iggy said:
one reason you may be having this problem is if you are using the windshield defroster the AC compressor is running also to dehumidify the air blowing on the windshield.
Wouldn't the MFD climate screen show AC on if that were the case?
No, because the A/C indicator in the Air Conditioning screen of the MFD indicates if the compressor is locked out or not. Not if the compressor is running or not.

I would strongly suggest leaving the A/C light on during the winter so you can get dehumidification assistance. iggy1iggy, I noticed in your sig that you have an 01. In that model the A/C compressor is belt driven and as such the ICE will run to run the A/C compressor, however on 04+ the compressor is electric and as such does not place a load on the ICE and does not require ICE to run for it to operate. Since the load is electric, the energy the A/C compressor uses will be from the HV system. So, that means battery power, but that battery power comes from a combination of power generated by the ICE while cruising and power that is collected through regeneration. I haven't noticed any significant MPG hit during the summer with the A/C running as it chooses, maybe 1 or 2 mpg, however during the winter I would expect A/C operation to be limited to defrost mode thus making its impact on electricity available in the HV circuit insignificant.
 

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Re: as a prospective buyer . . .

jeromep said:
sjerseycraig said:
My test for how well a car heats the cabin is pretty simple. When I was sill in college I used to make a number of trips home for holidays and weekends. These were 200+ mile journeys. Nothing worse than driving for 200 miles in a heavy goose down jacket, let alone a lightweight windbreaker. I always preferred to drive during the winter in shirtsleeves. So, if a car, during the dead of winter can keep you warm in your shirtsleeves the heater works just fine. The Prius does this very well.
Makes me think of the one December I drove my Chevette from CT to CA in late December on I80 in a record cold snap. It was -69 when we stopped somewhere. There were pieces of plywood at some gas pumps with spray painted letters saying not to turn off your car! The Chevette failed your test above misearably. We had ice on the inside of the windows! You had to drive and scrape and wipe, as your breath condensation would freeze to the windshield. It was me and a buddy from high school, and we were COLD! And the "heat" was on full blast. I remember stopping for gas, and we had to run shifts to fill the tank (no little latch to kee the pump going without a hand on it). I had on winter socks, LL Bean boots, long johns, sweat pants, jeans, T-shirt, turtle neck, flannel shirt, ski jacket, gloves and a hat on -- inside the car. This was for what? 2,000 miles I think, never mind 200 (we stopped in PA, but not after that).

god that car was a pile 'o crap!

Spike
 

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I use a block heater (I live in Finland) and although it is below 0C in the mornings, my MPG is about 45-50. I also bough my car last March and use 40/38 type pressure. With all the tricks I've learned about driving the Prius, the bottom line is: low speed (< 100km/h) implies high MPG.
 

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drtravel47,
If your commute is really short, there's probably nothing you can do to improve gas mileage beyond the mid thirties. But from a practical view, what does it really matter? Say your commute is 5 miles each way, then you're using a gallon of gas every 3.5 days instead of every 4 days. That's 61 cents/day instead of 54 cents/day.

Basically, you've already done the most important thing to reduce fuel consumption, live close to work. It's all minor improvements after that.
 

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but keep in mind. . .

that trips to and from work constitute only 25-30% of vehicle miles traveled. So having a Prius is still environmentally significant even if the drive to work is short.
 

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dontcheff said:
I use a block heater (I live in Finland) and although it is below 0C in the mornings, my MPG is about 45-50. I also bough my car last March and use 40/38 type pressure. With all the tricks I've learned about driving the Prius, the bottom line is: low speed (< 100km/h) implies high MPG.
Thanks, dontcheff - your experience matches mine.[/list]
 

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Re: but keep in mind. . .

sjerseycraig said:
that trips to and from work constitute only 25-30% of vehicle miles traveled. So having a Prius is still environmentally significant even if the drive to work is short.
Yes, the environmental benefits are very good in this situation, since most cars (other than the Prius and other SULEV/PZEV cars) produce a much larger amount of pollution during warm-up than at other times.
 
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