2007 Prius Touring use to get only 38 to 40 mpg

My 2005 Prius with 86K miles regularly got 48 around town and 49 to 53 on long trips. I sold it to my son and his wife, they are also getting the same mileage. I bought the 2007 touring used with 41K miles and have never gotten over 41 mpg highway, and around town is 38 to 39 mpg.

The biggest difference I can see is the power flow display shows it keeping the battery at 7 bars and will be charging the battery when I am driving uphill even with the battery at 7 bars. It has never let the battery get down to 4 or 5 bars even on long up hills.

- Current car, *** 2007 Prius Touring w/41K miles

Proposed questions:

Have you read This Thead Yet? *** Yes I have read all the low mileage threads.

- What region/state are you in? (if not already set by the user) *** Hillsboro, Oregon ( just outside Portland )

- What fuel economy are you getting and how are you determining fuel economy? (trip computer or manual calculations) . *** the best was 40.1 on trips and warm days, 38 to 39 around town. Using trip computer and manual calculations they are within .2 MPG.
- What fuel economy are you expecting and why? *** 48 around town, 49 to 53 on long trips 300 miles. Why? My 2005 Prius regularly got this mileage. I sold it to my son and his wife, they are also getting the same mileage. I bought the 2007 used with 41K miles and have never gotten over 41 mpg. For highway mileage we make trips from Portland to Seattle often and always got 48 to 53 MPG even with 4 people in the car or a load of stuff in the back. Why would my 2007 get about 10 mpg less than my 2005 ?

I know I am on winter gas in Oregon ( 10% ethanol ), that and winter cold normally cost me 3 mpg. So factoring that in, my 2007, 42 around town, 43 Highway. Compared with my 2005, 48 around town and 49 to 53 on the highway.
- Make, model, year, engine and transmission of previous car? (e.g. 08 Honda Civic Si 2.0L 4 cylinder, manual transmission) What was its EPA rating and what did you get on the same trips/commute? (EPA ratings can be found at ) *** Prius 2005 with Michelin Energy Saver A/S 195/65/15 tires and new Optima yellow top battery, 48 around town, 49 to 53 on long trips. My best mileage was 63 MPG for a 150 mile drive in south west Washington state.

- What are your tire pressures? *** checked cold. When purchased it was at 35 / 33, after our second trip to Seattle with poor mileage I upped it to 41 front, 40 back and got pretty much the same poor mileage.

- What are the approximate outside air temps? *** 45 to 60 normal days, 25 to 45 on a few cold days.

- How long are your trips? Around town, 5 to 10 miles, *** For highway mileage we make trips from Portland to Seattle often and with the 2005 Prius always got 48 to 53 MPG even with 4 people in the car or a load of stuff in the back.

- How much of it is city vs. highway? Roughly what's the average speed in overall and of each segment? Is there a lot of stop and go driving? *** Daily around town is 25 to 45 mph, suburban driving with 1/2 to 1 mile between stops. Highway is 55 to 70 based on speed limits. 3.5 hr drive time to Seattle. We make this trip every 6 to 8 weeks.
- What's the terrain like of your drives? (e.g. flat, gentle hills, steep hills, etc.) *** Around town mostly flat, Highway mostly flat with some moderate hills in southern Washington for about 30 miles.

- How are you trying to drive (e.g. trying to stay in electric only?) and how hard are you braking?
*** Moderate acceleration, avoid braking, glide to slow down. ( same style we got 48 to 53 mpg in our 2005 Prius.

- What modes are you using, if any? "normal", EV, power, eco? *** only has normal mode
- Are you "warming up" the ICE (internal combustion engine) by letting it idle after powering on? *** No start and go, except for the few days when it got down in the twenties and had to wait for it to be warm enough to keep windshield from fogging on the inside.

- Are you driving using D or B mode? *** D only

- Is your oil overfilled? (i.e. above the full mark on the dipstick) *** No, right on the full dot.

- HVAC settings? Are you using the heater, AC, auto mode, etc.? If using auto, what temp is it set to? *** Normally Auto 68, or off

- Are you using the factory tires and wheels? If not, please indicate tire make, model and size (e.g. Goodyear Assurance Fuel Max 185/65R15). *** Replacement tires came with car, Hankook Ventas V4se, 195/55R16 ( Standard size for Prius Touring )

- If reporting a mileage drop, did anything significant change on your car (e.g. accident, hit a curb or big pothole throwing off alignment, oil change/other maintenance/repairs, changed tires or wheels, etc.) or your commute? *** Went from 2005 Prius with 86K miles to a 2007 Prius Touring with 41K miles.

Have you had your alignment checked? Any pulling or abnormal tire wear? *** No pulling or abnormal tire wear.

Power flow screen info

*** I've been watching the power flow screen to observe its behavior and I've noticed that it relies on the gas engine far more than the 2005 used to. For example, when going uphill, it is at 7 green bars and it often is charging the battery, not drawing power from the battery. It has often been maintaining the battery at 7 bars in the green zone.
My 2005 would draw it down to 4 bars on long up hills and then charge to 7 or 8 on the long down hills.

Battery
*** The battery looks to be the original so about 6 years old. I have been checking on the 12 volt battery using the "hold info flash headlights 4 times" display technique and with a digital VOM. For the load, I turn on the headlights, rear defroster, windshield defogger fan and let them run for 2 minutes. While not the highest voltage it certainly is still in the usable range.

Display DVOM at the battery terminals
------------------------- ---------------------------------------
No load Load No load Load
12.0 11.1 12.3 11.64

When I turn the car on (engine running) the voltage goes up to 14.5 volts.


Does the ICE run longer than expected when you stop? *** Once warmed up, at a stop the engine does stop after its normal 7 - 10 second run time.

Do you upper grill block in the winter? *** No
What actual brand/grade of gas? *** Costco 87 octane
What oil weight? *** 5w30

Have you pulled the engine air filter? is it clean? *** Yes brand new

Have you taken a look at your MAF intake/sensor. *** Have not checked or cleaned it yet.

 

Thanks for the excellent answers.
I will start with 1, 2, 4, 5, 6, 7,
Re Tires, they are brand new and if going to Michelin AS and I got 4 mpg improvement it would take 1,463 gallons and 64,390 miles to offset the cost of new Michelin AS tires. So I will live with those.
On Fuel, it is the same fuel I got 49 to 53 miles per gallon with on the 2005, and the same I got my best 63 MPG with. So I don't think it is an issue but when I have a chance I will try shell for a while and see how that goes.
Re 70 mph. I only do that when on I5 on rural parts of Washinton state. When in Oregon it is 55 to 60 and I get the same 40 mpg. :-(

The thing that concerns me is the power flow where it is trying to charge the battery uphill when it is already at 7 bars.

 

Thanks folks,
I just put the tires up to 45 lbs all around ( max is 51 )
Put a note in to not use "Auto AC" , ( my wife also drive the car )
Ordering an Optima yellow top battery
Will clean MAF and check brake and tire free wheeling this weekend.

Then see how things go after a couple of weeks.

 

Installed the New Optima Yellow top battery
--------- on MFD---------------- on DVOM at the battery
--------- No load-- Load------------No Load
New ----12.6------ 12.1---------------13.6
Old -----12.0-------11.1---------------12.3
* put the dashes in, to keep it from compressing the lines like last time

Also cleaned the MAF

Jacked it up and:
Checked the Emergency Brake and it is not hanging up.
Checked the wheels and they are free rotating with no drag

I am going to stop here and see how mileage does for a few weeks. Once I baseline the new mileage with these changes I will try changing the gas for a few weeks and see how that affects things. Costco prices are the best around so I would have to see a significant increase in mpg to justify paying the higher price per gallon.

FYI, I got the Optima Yellow top at streetsideauto.com for just $147 w/free shipping
Shipped from Pennsylvania, came cross country fedex in 5 days.
I did not have to work with them at all as everything went fine.

 

After reading some info on cleanmpg.com there is info backing up that there are few reasons not to run tires up to the sidewall pressure. Also a person there has determined that 4 psi diff between front and back is optimum. So I now have my Hankook Ventus ( 51 psi max ) @ 49 / 45. This last week I also cleaned the MAF and installed the optima. My mpg is now up to 45.2 , it was at 38. I am thinking that most of that comes from running the tires up near the rated psi. This is without changing driving style and it has been with 3 or 4 people in the car. ( My inlaws were visiting for a few weeks ). Factoring in the normal winter driving drop of 4 mpg this puts the summer mileage equivalent at about 49 mpg and that is in line what I was getting with my 2005.

 

2nd tank after putting tires up to 49/45 ( max is 51 on the Ventus ) replacing the battery and cleaning the MAF.
My mileage is 47.2 (up from 38 to 39 mpg )
I used my micrometer and checked the tread depth to 10/1000 of an inch on the inside/middle/outside. I will track that and see if they are wearing evenly over time. Not wearing out the center.
My son put his 2005 Prius Michelin Energy saver AS tires up to 42/40 ( max 44 ) and his mileage went from 41.7 to 46.7.
Not bad for winter gas.

 

Had Seattle trip. Portland to Seattle with 26 miles around town before trip. Driving speed limit including 70 mph from Vancouver to Tacoma with wife using cruise control. 48.1 mpg. Trip back 60 mph no cruise control 50.8 mpg on winter gas.