Winter gas mileage

Yes, it's normal. It happens to non-hybrids as well, just not to the same degree. They have more "waste heat" to keep them warm.

If you turn off the heat when stopped the engine won't run. I use the "A/C auto" switch on the steering wheel to turn it off and on. On when the light turns green, off when I'll be stopped waiting. Once the car is fully warm I don't bother to switch it. The engine won't start as long as the coolant is above 63C (I use a Scangauge II to monitor the coolant temp).

Double check your tire pressure as well. It drops a lot with cold weather. You don't want to run lower tire pressure in snow or on ice. Tire manufacturers will tell you their tires work best with proper pressure in snow and on ice. I use 40 PSI front and 38 PSI rear (15" wheels, Nokian WR tires in stock size). I check monthly.

 

Yes, the mileage drop is normal. We live a couple of hundred miles north of you, and our summer mileage of around 54 drops to the mid to low forties in the winter. If I make any short trips, the winter mileage can easily drop into the high thirties.

The same thing happens with normal cars, only you don't notice it as much since the mileage is poor all of the time.

Tom

 

Palmetto,

With regards to the heat, have you experimented with lower blower settings? If I use lower blower settings I can generally keep the ICE from starting at traffic lights. So far this has been true in both summer and winter. I've been using the second blower position. Obviously there are times that more heat or AC are needed for comfort or safety, but at times where low settings are permissable it does really seem to help mileage.

Defog/defrost is probably the worst since both the heater and AC compressor are working simultaneously.

With both the Prius and other vehicles I try to get rolling ASAP (as long as visibility isn't compromised) without starting the heat. The quickest way to warm the engine is to put some load on it and I would prefer to do that by driving. In other vehicles as soon as the temp gauge starts moving I switch on low heat.

 

Join the club. I went from 47-48 in August/September to 35-39 in December, but I have a daily 10-minute city commute, so my mpg is usually down.

 

ICE = Internal Combustion Engine, or gas engine in other words.

The reason my mileage stays up is that my driving mostly consists of a 45 minute trip to Traverse City on occasion. Short trips are mileage killers. We live in a little village, and I walk everywhere. Only the trips into the "big city" are driven.

Tom

 

To repeat Tom, but in other words, short trips magnify the effect of cold weather because the engine spends less time in the warm efficient zone. I'm in the same situation as Palmetto, so I'm guessing Palmetto's daily commute is between 5 and 15 minutes each direction.

 

Observations from the Scangauge II in cool weather (close to 0F).

Yes, it takes some time to -fully- warm up a Prius. Three blocks at 60-70 km/hr (40-45 MPH) will get you nice hot air blasting out of the vents.
After 5 min or so of -driving- (waiting at lights etc. doesn't count), the heater will not prevent the engine from shutting down at lights, though if the wait is long enough, it could restart.
After 20 min of -driving- the engine etc. is fully warm, and it's unlikely the engine will start while waiting at lights.

Note that the engine will cool off if you are coasting downhill a lot.

The heater set temp being higher or the fans running at higher speed -can- cause the engine to start sooner. This is simply because when the engine stops there is only so much energy in the heater core. If you remove it more quickly, you will reach the engine start trip point (about 63C coolant temp) sooner. Don't confuse this effect to directly -causing- poorer mileage. You can operate the Prius so the heater uses -waste heat- only, and when you do so the heater has no effect on mileage. e.g. make sure the engine doesn't start when you are waiting at lights etc. I run my heater at a set point of 22C (about 73F) with no effect on mileage, because I don't allow the engine to start when I'm stopped.

Yes, ICE is Internal Combustion Engine.
MG is Motor Generator (there are two in a Prius). MG1 is the smaller of the two.
An engine produces power from conversion of one form of energy to another. e.g. burn gasoline to turn a shaft.
A motor uses power to turn the shaft. e.g. electrical energy from a battery or air pressure from a tank.

 

Hey Palmetto, what part of Western Michigan is your home turf? I spent a lot of years in the Kalamazoo area.

Tom

 

I'm in the metro Detroit area and I'm crying about my lower than normal MPG too. It's the weather. I don't think we had temps this low until February last season. We didn't seem to have much of a fall or Indian summer.

I do have the EBH this year which really helps in the morning--but I wish I had some place to plug in while I'm at work. I also have the grill blocked.

Driving habits make a bigger difference now than ever--watch the fast starts, coast lots, combine trips, check the tires and all.

I was happy this morning commute--about 14-18 degrees and I still arrived at work with 51.3 mpg on the mfd.

Has anyone ever had problems with their grill blocking foam falling out at the car wash?

Prius Prime

 

Be sure to install something to block you grill in the winter (pipe insulation). It will improve your winter efficiency at least 2 MPG

John

 

For those experiencing mid-grade winters, yes.

For those that endure the extremes (routinely seeing below 10°F) the benefit translates mostly to lots of heat for keeping you warm.
.

 

Car wash? What is a car wash? Yeah, i would imagine if you have foam pipe insulation stuffed in the upper grill, it could be knocked out by the high water pressure. For the lower, you need to hold it in with plastic wire ties. I found 3 works well.

 

If you use the 1/2" type for each slot, you actually have to tear it out in the spring. The stuff doesn't move that way, regardless of what you hit it with.
.

 

Don't know about the car wash as I always hand wash, but I've had to use plastic ties on the upper grill. The compression fit works for a few weeks, then the foam works its way out enough to catch the slip stream.

 

I had major surgery 7 weeks ago. So, I've been laid up till about now. And I just now got in my Prius. The wife had been driving it. I asked her how she managed to take my 52 mpg down to 39!!!!!!!!!!!

Well, I drove it for hours today. I did BARELY better than her.

This winter mileage sucketh!

 

You're taking a big hit not only for the colder temps but it is amlified by your short commute of 10-15 minutes. 2/3 of your trip is likely spent just warming up the coolant. I recommend you concentrate on this part of your trip and pulse the pedal in addition of taking a favorable terrain for your route (if possible). A history of my seasonal stats going into my second winter:

I try as much as possible to limit my short trips in cold temps.