Mileage Declining

LarryBA · 12-03-2007, 11:35 AM

When you talk about Mileage issues to the Toyota corporation or dealers, it is like the "deer in the headlights" stare - no one is home. One reason I dropped mileage is when I replace my original tires at about 35,000 miles. A lot of web research revealed that Prius's come with Low Rolling Resistance tires, such as the GoodYears that the 2005 shipped with. The BF Goodrich tires I replace them with, while meeting all specs, are not LRR tires. Wow, was I shocked and my neighbor who has the same model experience the same thing. I lost 7 miles per gallon until I beefed up the tire pressure to 40 in front and 38 in back. Then, I got back around 4 of the 7. But, now I notice that my mileage continues to be low. For 3 years, I averaged about 48 in winter, 50 in summer. Now, about 44 in winter. The car mileage takes a bigger dip now when the car is first used. I never noticed this before. Right now, I'm at about 42 mpg, never that low before.

Has anyone had any success when servicing their Prius's to get anything adjusted that helped? I just get the "it is run by a computer and we can't change it."
Thanks

bwilson4web · 12-03-2007, 01:09 PM

Quote:

Originally Posted by LarryBA

. . .
Has anyone had any success when servicing their Prius's to get anything adjusted that helped? I just get the "it is run by a computer and we can't change it." . . .

Yes, in no particular order:

changed transmission oil at 53k miles - made a measured reduction in rolling resistance. Transmission studies continue.
rear wheel alignment - used shims to minimize rear wheel toe and camber with a reduction in rolling resistance.
sumitomo tires at max sidewall - running their low rolling resistance, T4 tires, at 51/49 helps.
spring/fall lubricants and filters - in the fall I put in 5W-20 and the spring 5W-30 with new filters. In the fall, I also use a throttle cleaner and brush and a container of injector cleaner.
use higher energy fuel - in Huntsville, Shell, Exxon and Chevron gasolines measure the highest ICE shaft power per gram.
using engine and transmission pan heaters - part of a study, no final results. However, it appears to cut the warm-up interval significantly.
use front grill block in the winter - still under study.

Bob Wilson

**Tideland Prius** · 12-03-2007, 01:41 PM

A couple of extra things:

- check to make sure your oil isn't overfilled
- check your engine air filter. It might be time to replace it.

jstack · 12-03-2007, 04:18 PM

the most important option is the driver.

If you get the car up to speed and let up just a tiny amount you will see you mpg jump up. Sometimes you will actually speed up a little. This seems to be the way to make the CVT transmission go into enconomy mode by being in a hight ratio that you may be.

This one little method is a little like the surge and glide but not as noticable. I do it and get 55-75 often. I have had up to 84 mpg on my 20 mile each way commute to work and back for 40 miles. I even car pool with 2 others and a bike rack on the back. The driver can make the biggest difference.

I have goodyear viva2 tires, LRR
Keep air at 36-40
drive at or just below speed limit.
stop at lights and stop sign gradually to get max regen, no hard braking wasting momentum and brake pads for no reason.

al881 · 12-24-2007, 01:41 PM

I average 54/high 40's.

I just got done with an oil change and they showed me that the tires need
replacing(I'm at 46K).

They're price seemed to be too high (75 per tire) and also a recommended
front end alignment as well brought this to over $500. (I'm talking Ernie Boch, Mass dealer).

But reading this thread I didn't realize the auto used a LRR type.
I'll see what a tire company wants this week.

Also, I have to agree with "jstack". I have owned 3 Prius. (01, 05 and 06).
The wife drives the 06.

My car is used for business commute. (half back roads. half highway 75-80).

Anyways the highest I've achieved is 61 MPG and I always let up on the
accelerator. It took me many months to get the wife to do this after seeing her low MPG, but now she is at low 50's.

Question, do I need to do a front end alignment after putting on new sneaks?

thanks AL

N3FOL · 12-29-2007, 05:25 PM

It is good practice to have your alignment checked everytime you put new sneaks. There is no way one can tell whether your wheels are aligned by using the naked eye.

San_Carlos_Jeff · 12-29-2007, 11:00 PM

I feel your pain. I'm having the exact same "problem" with my 2005. In my case it's directly attributable to the Bridgestone's I got. They are nice and quiet and corner better than the OEM tires, but I'm kicking myself every time I look at the MPG. It's a struggle to get over 43 where I used to get just above 46 w/o much effort.

radioguy · 12-29-2007, 11:09 PM

I can't speak to what everyone else is seeing, as my driving varies all over the place (I live in the Houston, Texas area). Some days bad, some days great. Don't get me wrong...I love the car, and would buy another one when I run this one into the ground.

Speaking of, and my reason for posting this-I bought my stock Prius in June of '05, and now have close to 91K miles on it. How many others on the list have this kind of mileage (or more)? What can I expect?

Fred Morton
Houston, TX

F8L · 12-31-2007, 11:27 PM

It's the tires. Very simple.

I have an '05 with 55k and I'm getting the best milage I ever have now that I have the stock rims/tires back on the car.

Aftermarket tires will hurt your milage if they are:

1) Heavier than stock
2) Stickier than stock
3) Higher Rolling resistance than stock
4) Require higher air pressure and you do not adjust for it
5) etc

paprius4030 · 01-01-2008, 09:46 AM

I wouldn't blame all of Toyota, I think it's all about having a good dealer. When I brought my first Prius in for it's first service, I was introduced to the Prius tech. He sensensed I was very interested and up on Prius issues and he confirmed alot of what we talk about here. He talked about why it's important not to overfill the oil, keep tires at 42/40, keep a good check on ICE air filter ect. I'm lucky my dealer is very up on the Prius.

12-03-2007, 11:35 AM	#1
LarryBA Junior Member Join Date: Nov 2004 Posts: 1 My Car: Package: Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 0	Mileage Declining - 3 yr old 2005 model When you talk about Mileage issues to the Toyota corporation or dealers, it is like the "deer in the headlights" stare - no one is home. One reason I dropped mileage is when I replace my original tires at about 35,000 miles. A lot of web research revealed that Prius's come with Low Rolling Resistance tires, such as the GoodYears that the 2005 shipped with. The BF Goodrich tires I replace them with, while meeting all specs, are not LRR tires. Wow, was I shocked and my neighbor who has the same model experience the same thing. I lost 7 miles per gallon until I beefed up the tire pressure to 40 in front and 38 in back. Then, I got back around 4 of the 7. But, now I notice that my mileage continues to be low. For 3 years, I averaged about 48 in winter, 50 in summer. Now, about 44 in winter. The car mileage takes a bigger dip now when the car is first used. I never noticed this before. Right now, I'm at about 42 mpg, never that low before. Has anyone had any success when servicing their Prius's to get anything adjusted that helped? I just get the "it is run by a computer and we can't change it." Thanks

12-24-2007, 01:41 PM	#5
al881 2001,2005,2006 prius Join Date: May 2005 Location: Massachusetts Posts: 3 My Car: 2006 Prius Package: #4 Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 0	Re: Mileage Declining - 3 yr old 2005 model I average 54/high 40's. I just got done with an oil change and they showed me that the tires need replacing(I'm at 46K). They're price seemed to be too high (75 per tire) and also a recommended front end alignment as well brought this to over $500. (I'm talking Ernie Boch, Mass dealer). But reading this thread I didn't realize the auto used a LRR type. I'll see what a tire company wants this week. Also, I have to agree with "jstack". I have owned 3 Prius. (01, 05 and 06). The wife drives the 06. My car is used for business commute. (half back roads. half highway 75-80). Anyways the highest I've achieved is 61 MPG and I always let up on the accelerator. It took me many months to get the wife to do this after seeing her low MPG, but now she is at low 50's. Question, do I need to do a front end alignment after putting on new sneaks? thanks AL

12-29-2007, 05:25 PM	#6
N3FOL Senior Member Join Date: Dec 2007 Location: Stewartstown, PA. Posts: 772 My Car: 2008 Prius Package: #4 Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 0	Re: Mileage Declining - 3 yr old 2005 model It is good practice to have your alignment checked everytime you put new sneaks. There is no way one can tell whether your wheels are aligned by using the naked eye.

12-29-2007, 11:00 PM	#7
San_Carlos_Jeff Senior Member Join Date: Oct 2005 Location: Northern California Posts: 553 My Car: 2005 Prius Package: #3 Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 0	Re: Mileage Declining - 3 yr old 2005 model I feel your pain. I'm having the exact same "problem" with my 2005. In my case it's directly attributable to the Bridgestone's I got. They are nice and quiet and corner better than the OEM tires, but I'm kicking myself every time I look at the MPG. It's a struggle to get over 43 where I used to get just above 46 w/o much effort.

12-29-2007, 11:09 PM	#8
radioguy Junior Member Join Date: Jul 2005 Posts: 5 My Car: Package: Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 0	Re: Mileage Declining - 3 yr old 2005 model I can't speak to what everyone else is seeing, as my driving varies all over the place (I live in the Houston, Texas area). Some days bad, some days great. Don't get me wrong...I love the car, and would buy another one when I run this one into the ground. Speaking of, and my reason for posting this-I bought my stock Prius in June of '05, and now have close to 91K miles on it. How many others on the list have this kind of mileage (or more)? What can I expect? Fred Morton Houston, TX

12-03-2007, 01:41 PM	#3
Tideland Prius Super Moderator Join Date: Oct 2004 Location: Canada Posts: 14,171 My Car: 2005 Prius Package: B Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 12	A couple of extra things: - check to make sure your oil isn't overfilled - check your engine air filter. It might be time to replace it.

12-03-2007, 04:18 PM	#4
jstack Senior Member Join Date: Jul 2005 Location: Chandler Arizona Posts: 152 My Car: 2005 Prius Package: Base Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 0	the most important option is the driver. If you get the car up to speed and let up just a tiny amount you will see you mpg jump up. Sometimes you will actually speed up a little. This seems to be the way to make the CVT transmission go into enconomy mode by being in a hight ratio that you may be. This one little method is a little like the surge and glide but not as noticable. I do it and get 55-75 often. I have had up to 84 mpg on my 20 mile each way commute to work and back for 40 miles. I even car pool with 2 others and a bike rack on the back. The driver can make the biggest difference. I have goodyear viva2 tires, LRR Keep air at 36-40 drive at or just below speed limit. stop at lights and stop sign gradually to get max regen, no hard braking wasting momentum and brake pads for no reason.

12-31-2007, 11:27 PM	#9
F8L Collecting Data on Nature Join Date: Aug 2006 Location: Sacramento, CA. Posts: 3,997 My Car: 2005 Prius Package: #4 Nominated 1 Time in 1 Post TOTM Awards: 0 Friends: 15	Re: Mileage Declining - 3 yr old 2005 model It's the tires. Very simple. I have an '05 with 55k and I'm getting the best milage I ever have now that I have the stock rims/tires back on the car. Aftermarket tires will hurt your milage if they are: 1) Heavier than stock 2) Stickier than stock 3) Higher Rolling resistance than stock 4) Require higher air pressure and you do not adjust for it 5) etc

01-01-2008, 09:46 AM	#10
paprius4030 Senior Member Join Date: Aug 2004 Location: Pocono's, Pa. Posts: 1,079 My Car: 2008 Prius Package: #2 Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 1	Re: Mileage Declining - 3 yr old 2005 model I wouldn't blame all of Toyota, I think it's all about having a good dealer. When I brought my first Prius in for it's first service, I was introduced to the Prius tech. He sensensed I was very interested and up on Prius issues and he confirmed alot of what we talk about here. He talked about why it's important not to overfill the oil, keep tires at 42/40, keep a good check on ICE air filter ect. I'm lucky my dealer is very up on the Prius.