Milege Drop on 2006

As tires wear they get smaller (24.5 inch diameter becomes 24 inches). This changes the odometer calibration by about 2% and falsely indicates a 2% (about 1 MPG) reduction in MPG when putting on new tires. In addition, your original GY Integrity tires were the version made in Japan and the new ones were most likely slightly different tires made in the US (check the sidewall). They may have a higher rolling resistance than the original tires.

JeffD

 

Tires take time to break in. During this break in period, your mileage will suffer.

 

Ditto from Dallas. Really high temps do hurt, but *don't* avoid using the A/C. The A/C also cools the battery system, and if the battery gets too hot MPGs will drop even more.

What are the tire pressures?

 

I'm having the same problem too. I'm on the E coast of FL and my mpg has dropped from a steady 52 down to 49 and still heading downwards. I just got new tires last week and it has dropped that much already. They filled the tires with nitrogen saying that should help fuel economy, they're doing it to all new tires. I think the ethanol has made a dramatic difference also. I can't find any stations that don't have it. I thought maybe some of it is the summer heat 90+. The winter months I had great gas mileage. My driving habits haven't changed I see where others are using greater tire pressure to get better mileage. I guess it would be ok to add air to the nitrogen they put in the tires to take it up ??

 

1. Nitrogen does nothing for MPG (or anything else, it is a fund raiser). Increasing the PSI does help MPG but stay below the rated MAX (on the sidewall - 44 for Integrity) and 2 lbs higer in the front than the rear (compensates for the heavier front end of the Prius).
2. "Tire break-in helps MPG", an often stated, but never proven assertion.
3. Short trips significantly lower your MPG (as does wet weather). Have your driving habits changed?
4. Overall, a Prius can be expected to average about 48 MPG in warm (not hot, as AC cost MPG) weather and in the low 40's in cold weather. Very few people manage to average over 50 MPG ever(I don't, even in warm weather - see the attachment).
5. Next time buy true LRR tires instead of the poor performing GY Integrity tires. I run Nokian WR tires on my Prius, but they (and the WRg2) are optimized for harsh winter weather. Take a look at the Nokian i3 summer tires for warm climates. Nokians are available from Nokian Tires - Winter Tires, Snow Tires and much more from the Tire Factory at reasonable prices and your local tire store can mount them for about $40.

JeffD

 

Even in hot dry weather the milage will generally drop due to battery heat the the need to run the A/C much more often. I can still maintain 50-53mpg tanks with a few 55-58mpg tanks but it is MUCH harder to get those high numbers in the Sacramento summer climate with 98-105deg days.

The tires do need to break in as rolling resistance does go down with use as stated by many manufactures.

I just had the Nokian i3s installed today and will be tracking the mpg change after my hiking trip which will give me a nice 500mile break-in.

 

I have a 2008 Prius as well and I only get 33-35 MPG. When I bought it used one year ago I was getting around 38 MPG. I didn't realize that they should be getting close to 50 MPG. I too am at a loss as to what the problem might be. I have been searching for an answer here on the forum as the Toyota dealer told me there was nothing wrong with my car. Very frustrating!

 

they don't make i=3's anymore. but there is a replacement.

 

interesting. i had 3 places including tire rack tell me i-3's are no longer available. my daughter had them put on when the originals wore out around 45,000 and her mileage stayed about the same.

 

what about 12 volt battery?

 

It would help if you answered the questions as directed in your other thread at http://priuschat.com/forums/gen-ii-...849-very-low-gas-mileage-why.html#post1156382.

As for "they should be getting close to 50 MPG", as you stated, you "travel mostly short distances". You will not get close to 50 mpg with short drives.

 

My '05 base has 159,000+ about 3 weeks ago the mileage went from 50~54 road trips to 43. Noted several issues: before this happened I could get as much as 22 MPG in stop and go with gas motor only coming on when the battery got too low. Now it jumps to motor and indicates charging the battery and initial MPG is in the 4 MPG range. Dealer replaced the aux battery. cleaned the air door and says it's A-Ok, not so. Another issue is the "deadly" traction control no longer effect hard acceleration, not my normal driving mode but necessary sometimes to avoid an accident.
In June the car was in for the recall re: gas pedal though never had a problem and now I wonder if during the process a new computer load is part of the fix?

 

You are reading my post from 2008.

 

I live in NW FL and have had my 08 only a few months. Bought it with less than 13k and now close to 20k. I changed my driving habits and now up in the 50's mpg. It's humid where I live and my commutes are 23 miles one way to work. I run the AC all the time except the last mile or 2 before I get back home.

 

I have tried to download the information on my car and it's giving me an error message saying I have to have 5 posts before I can download a URL or something to that effect? Also, can you tell me an easy way to find your post and is there any way to get replys sent via email? Thanks in advance for any help you might be able to provide.

 

I'm not sure what you're referring to, but I have a wild guess.

There's a sticky thread at the top of this sub-forum (Gen II Prius Fuel Economy). It has the title:
Sticky: Fuel economy complaints/queries? Please copy, paste & answer these questions, esp. if you're new

Please fill out and answer the best you can, preferably in the other thread you started.

For any thread, you can receive email notification of replies by going to Thread Tools > Subscribe to this Thread.

 

I too live in Florida and am seeing the same issues with my 2007.

I checked my log and numbers for last summer are in the 50's (53ish) and now I'm lucky to get 47.

I did get new tires + 30k mile tune up + the pedal warranty work and noticed the drop immediately after that.

I did some spot tests on my mileage before and the manual calculation seemed to match the computer but will do the same today or tomorrow just in case (maybe there was a computer update?).

Something happened in that service but I don't know if I just need to break in the tires or if it's something else. Even when I got the car and didn't know how to drive it properly, my mileage was higher. Plus my commute and driving style hasn't changes in the last few years.

If you have any ideas, let me know and I'll post my manual mileage info in the next couple of days.

 

Let me take a wild guess and say you have less than a couple thousand miles on these new tires and/or they are not low rolling resistance specialty tires?