Cold weather MPG? Always charging?

Cold weather and snow will cause a mileage drop in any car. You see it especially in a high mpg vehicle like the Prius, since the numbers are so high to start. We average around 54 mpg in the summer, but are getting about 42 mpg now.

As for constant charging, the Prius will run the ICE more often and for longer times in the winter. It needs to keep the catalytic converter warm, and heat the inside of the car. As a result, more electricity is available for charging, so it might as well use it. There are also so more subtle effects involving the ability of the battery to store a charge.

Tom

 

I'm experiencing the same "cold weather" effect as Geoffrey... about 8-10 MPG reduction with OAT running 25ºF - 40ºF. Part of the loss is due to the ICE running more to keep the cabin warm. Still, I get about twice the fuel efficiency in the Prius as in our Camry, so I really can't complain. I have done the 'partially blocked grill' thing which seems to help a little.

Another factor in my case is only ~2,000 miles on the odometer so my '07 Prius is still not broken in. It took about 8,000 miles for my 2004 to achieve its best fuel economy.

 

My mileage numbers are almost identical to Tom's - 54 summer to mid 40's winter. I have always seen substantial decreases in winter, in part because we have always driven high - mileage cars that show the difference more dramatically.

Cabin heat is a factor, no doubt - and we leave the heater off until the engine is warmed up (don't know if this really helps, but it seems to). Sometimes we forget...and it feels like our old VW bug!

Lower efficiency must be a factor in winter cold.

Compromised rolling resistance (snow on road, slush) seems particularly troubling for this car.

We always see a sudden decrease as winter approaches, and I have always figured the formula for the gasoline changes a bit for cold weather, with a noticeable difference in fuel economy.

Jim

 

Here I was averaging around 46-49 MPG in the summer and now im averaging around 33 MPG in town and around 42 MPG on the highway.... and we just got 10 inches of snow and It has been holding in the 0's - low 10's for about 3 weeks now... still, I m getting far better mileage than most people so I do not feel too bad... although I miss my 48 MPG average from this summer

 

My current Prius (a 2006) was purchased about 8/1/06. For the last 5 months of 2006 (half of which time I had the snow tires on), I averaged about 44 mpg. For the first 5 tanks in 2007 (and it's been very cold here in MN for the last 3-4 weeks), it's dropped to an average of 37. I have a fairly short commute, under 6 miles one way.

rpm

 

My first winter with the Prius, we had about a week of -35 to -40. I didn't have a winter front. The ICE ran constantly, I just about froze, but the battery SOC was fully green. I think it's normal for cold temps.

This winter we've had almost 6 weeks of bitterly cold weather. With the winter front, I'm toasty warm and the battery will usually be in the high blues.

 

<div class='quotetop'>QUOTE(Geoffrey B. @ Feb 15 2007, 06:22 AM) [snapback]390767[/snapback]</div>

If cold enough, absolutely. Also, if you're not using the block heater - definitely.
Coasting and braking (and park) are when the batteries charge - normal.
Hang in there through summer and I'll bet you'll be happy with it.