My 2005 has begun to take a MPG hit

The only MPG hit I've taken with my 04 is cold weather related. Have you checked your tire pressure and oil level lately? Low tire pressure and high oil level will reduce MPGs. I doubt that you have a traction battery problem with an 05.

 

I will second that. When my MPG drops, I first check the tire pressure, then remember the cold weather means a drop in MPG.

 

Very impressive stats Tony and nice MPG figures you have been posting lately. I have not gone to near the detail in recording as you, but I too so as much as a 4 to 5 MPG hit in cold weather in our '05.

 

Mpg

My MPG went WAY down 20%+ when I changed tires. I replaced them with the recommended tires and pressure and had a tune up (have 45k miles on my '04) and it's still really bad. I used to get close to 50. Anyone have any ideas????

 

Have you guys done the obvious comparisons with respect to temperature, fuel formulas, road surface changes etc.?

1. Have the streets or highways on your normal commute been repaved?
2. Are you doing long-term calculations regarding temperature?
3. Have you tried switching from your normal gas station?

Sandra, what tires and size did you replace the Integrities with? What pressure are you running them at? Have you done any other mods that would add weight or suck up battery amperage?

I have an 05' Prius and because of my mods I was only averaging 44-46mpg (75-100deg temps). I swapped back to the stock tires/rims and took out the extra weight of my subwoofer boxes and now I am getting and average 52mpg over the last 5 tanks or so despite temps dropping to the 30s-40s.

 

I bought the Potenza G 009 which is what both the dealer and tire store recommended. When my milage went down so much I went back to the tire store and had them fill them to the max, which they did. I checked with Toyota and they concurred that the tire pressure was good (highest possible). I'm at a loss and wondering what else I can do. Last tank I only got 40 mpg and I'm driving in the same areas and I'm in N. California, so the weather's not an issue (besides, this started last summer). My driving style hasn't changed either, I drive it really conservatively (using the engine to break, am really good about gliding to lights and stop signs etc) Any suggestions would be welcome.
Thanks,
Sandra

 

What area do you live in Sandra? I'm in Norcal as well and my milage had never been great due to the speeds we are usually "forced" to drive or the weird commute in some areas.

Tires can make a pretty big difference. I swapped mine back to stock and my milage shot up despite lower temps.

 

I'm convinced it is not my driving style, road changes or weather that's causing the diminishing mpg. Is there anything I can do to the engine? Have you heard of this before? When I talked to the dealer, he told me a mechanic at the store had the same issue with the tires. Do you think I should switch out my tires? That seems really wasteful (and expensive) as a fix...

 

There isn't anything you can do to the engine (ICE) for what you are experiencing. I believe it is caused by the tires you're running. Was the mileage drop right after the tire change? Why did you change tires from the OEM tires?

 

Tire Rolling Resistance Matters.

I've got an '05 Prius and am looking for new tires. Car and Tire companies are well aware that rolling resistance matters to fuel economy. OEM tires are selected for good milage, so the EPA test #s will be great, but they typically wear out after 20 or 30k miles. After market tires are sold on traction, treadwear and temperature performance characteristics.

Basically, they know how to make an efficient tire, but it might not last quite as long, or corner as well in the rain. Tire companies think we don't pay attention, so they don't optimize after market tires for efficiency and of course they don't quote the performance either.

The California Energy Commission is testing some tires and will publish test results in the next year or so. We can help by letting tire companies know that we are paying attention and want them to specify and guarantee the rolling resistance of their tires.

 

yes, the mpg went down the moment I started driving on the new tires. I needed new ones as I have 40k on the old ones....I guess I'll just have to wait until my next tire purchase....
Thanks for the input and let me know if you have any further thoughts.

 

oil ,tire and cold weather

I have a 2006 prius .my mileage has dropped alot this year.
I had winter tires put on last year so I had a rough idea what to expect but then I noticed the over fill on the oil , another drop .tire pressure is up (40/38)so i think I'm ok there I went fron 49 mpg last year to 42 this year . Can the oil being over filled do that much of a change ?
I did get the dealer to drain the excess out (he said not a big deal but we will do it for you )after I showed him the dip stick and said this was the second time & the manual says .He didn't say a word except OK.
How much damage can be done by this and what kind of damage ?
If I keep an eye on them will it straighten out with no further over fills.
Oh also my grill is blocked already for winter . Any ideas anyone??

 

Did they do an oil change at the same time as installing the tires?

One of the more notorious 'fixes' is putting 5 quarts in a 4 quart tank, over filling the car to sell another quart of $5/quart oil. Check your dipstick and see if it is at or under the "F" line.

Bob Wilson

 

yup

It has been at least a tank of gas since the oil check ,the mileage is still low 43 it did better last year same tires and all . will it ever go back up .how does the over fill affect the mileage ?

 

I have 86,000 miles on my 2004. I have not experienced any unexplained drop in mileage.

 

I've had the oil changed a couple of times (once by the dealer) and my mileage still stinks. Today I barely broke 40....

 

I have not had much experience with this, but the thing I am thinking of is the gasoline, changing form summer blend to the winter blend. Sounds loke BS, I know but there is a difference. The other consideration may be ethanol added to the fuel. i read in PC that the ethanol will decrease the MPG as opposed to straight gas.