Over the last month I've noticed a 10 mpg decline. I was getting around 54mpg now I'm getting 43mpg. I have an 05 Prius and I just hit 30,000 when it started to go down.

I live in Wisconsin and it has been getting colder but it seems like a large decline.

Has anyone else noticed this? Is this common during winter months or is this something I should have checked out?

Thanks

Yes:



There are two mitigation strategies:

(1) block heater - ICE and possibly transaxle pan heater
(2) route planning - increase the low-speed part of the initial commute by trying to stay below 30 miles per hour for at least 1-2 miles

GOOD LUCK!

Bob Wilson

Operation Iraqi Oil Freedom:

Automatic, stock, project car.

My other 1500 cc car:

Automatic, stock, backup car.
Free speech, dialog and knowledge thrives without the poison of SPAM.

Winter gas could also be a contributing factor. That would work in combination with the low temps to lower your mileage.

(that's what my car tells me, so it must be true)

Rolling resistance also increases, as well as your tire pressures declining due to colder temperatures can affect your mileage too. You might want to check your tire pressure to see if there has been a drop since you last checked and possibly raise them up a bit higher to mitigate the cold weather FE drop. Just look at the history of the Prius in my sig, you can see the pitiful tanks from it's first winter.

-Justin Fons
www.MilwaukeeHybridGroup.com

I own a TCH and I live in GreenBay. I realize from my last drive to Lacrosse that my milage declined from 43 to 38 MPG. During that time the temperature was around 39F. Recently I also realize that during my 3 miles city commute each way, i seldom got over 30MPG.

This question comes up this time each year when the weather turns cold. There are a lot of threads about it priorly but the one below from the Hybrid Camry forum is the most recent.


http://www.greenhybrid.com/discuss/a...ase.10694.html

If its very cold, and your trips are short and it's rainy/snowy/icy and it windy any vehicle could lose up to 60% of it's 'normal' fuel economy. A Prius could be in the mid 20's while a 4c Camry in the low teens. Nonetheless you will still gain 40% in fuel economy over a similar ICE type vehicle even at the reduced FE values

Lifetime fuel usage: 2.1 GPC ( 1.99 recent )

Hi,

I bought a 07 Prius a few weeks ago, and so far the best mileage I can get is no better than 48 mpg on high way and even much lower in city. I keep seeing ads on TV that claim an average mileage of 55 mpg (51 on high way and 66 in city) for Prius, and in no way I can see my Prius reaching such a goal. I don't have any bad driving habit and have been doing all I can to see if I can reach the advertised mileage. Am I misled or is something wrong with my car?

Thanks.

Welcome to the club.
My first tank was 39 MPG and I briefly thought about taking the car back. But instead, I decided to study the problem and coming to GreenHybrid.com is an excellent first step.

Today, the only standard test is the EPA profile. The highway test has an average speed of 48 miles per hour. But this shows what I've found:


Over time, a lot of folks have looked at how to get better Prius performance. I've tried to collect those tips in the Prius FAQ. You might take a read and see if any of them help. I also understand Wiki has a nice write-up.

My best recommendation is to join the mileage database and start recording your mileage. Then apply individual changes to different fill-ups. Over time, a couple of months, you'll be able to find what works and doesn't work.

You're in for a treat as you learn how to master the Prius. It will take some changes but they aren't that hard.

GOOD LUCK!

Bob Wilson

Operation Iraqi Oil Freedom:

Automatic, stock, project car.

My other 1500 cc car:

Automatic, stock, backup car.
Free speech, dialog and knowledge thrives without the poison of SPAM.

Same situation here, with an '07 Prius in service only two weeks. I was averaging 48.4 mpg, but then the wife drove the car and lowered it!

Besides the cold weather, there is also the issue of engine break-in. I don't expect best mileage on a brand-new motor. I had a Ford Escort years ago. The first time I checked highway mileage I got 30 mpg. After 5,000 miles, the highway mileage improved to 35 mpg. I don't think it is unreasonable to expect an improvement in my Prius gas mileage after giving the motor a chance to break in.

By the way, I checked tire pressures the day after i brought the car home, and all 4 tires had 33 psi of air. I raised the fronts to 37 psi and the rears to 35 psi. I will probably go ahead and raise tire pressures some more very soon.

Harry

Hi Harry,
Shoot, just driving with my wife lowers my MPG ("That truck just passed you! You're going too slow.") <grins>

Bob Wilson

Operation Iraqi Oil Freedom:

Automatic, stock, project car.

My other 1500 cc car:

Automatic, stock, backup car.
Free speech, dialog and knowledge thrives without the poison of SPAM.