Low fuel economy - what else in this section

- What fuel economy are you getting and how are you determining fuel economy? (trip computer or manual calculations)
Around 31.7 from trip Computer

- What fuel economy are you expecting and why?
Gen 2 Prius should get in the 40 range

- What are the approximate outside air temps?
San Diego CA usually around 68 to 85

- How long are your trips?
7 to 20 miles, usually less than 10

- How much of it is city vs. highway? Roughly what's the average speed in overall and and of each segment? Is there a lot of stop and go driving?
Even mix of both but I live at the top of a small hill (about 1 mile drive up and down) and main access road to freeways. City speed about 40, freeways 65 to 70

- What region/state are you in? (if you haven't set your location in your profile)
San Diego CA

- What's the terrain like of your drives? (e.g. flat, gentle hills, steep hills, etc.)
Mostly flat with a few small hills

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

How old is your 12v battery? What is the voltage reading of your 12v battery after sitting over night? (Method Here)
Brand new just replaced.
Test Mode 12.4
Acc Mode 12.1
Started Mode 14.2

Have you had your alignment checked? Any pulling or abnormal tire wear?
Alignment is getting re-checked, recent front passenger tire abnormal but even wear

- 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).
Michelin Defender standard size for car
- What are your tire pressures?
not sure but just had them checked at discount tire - I think about 33
- Make, model, year, engine and transmission of previous car? (e.g. 08 Honda Civic Si 2.0L 4 cylinder, manual transmission) What did you actually get on the same trips/commute? (Please give us actual numbers, not EPA ratings.)

Not relevant, have had this car for over 8 years and lived in different city when I owned a different car.

- How are you trying to drive (e.g. trying to stay in electric only?) and how hard are you braking?

Normal, keep an even speed without trying to do any hard acceleration

- Are you "warming up" the ICE (internal combustion engine) by letting it idle after powering on?
No

- Are you driving using D or B mode?
D Mode

- HVAC settings? Are you using the heater, AC, auto mode, etc.? If using auto, what temp is it set to?
Mostly AC at 71

- 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?
I just replaced the 12 volt battery and put in a reconditioned traction battery. My mileage has not shown any significant improvement.
I own a 2007 Prius and the gas mileage has been going down steadily. I figured it was due to the batteries so I replaced both of them but have not seen any real improvement.
Driven over 50 miles but I can tell nothing has really changed.

 

The car has 291,000 miles on it. The trans-axles were replaced last year. The engine was replaced several years ago and has 145,000 miles on it. The 12 volt battery was replaced this week. The traction battery was replaced this week with a rebuilt/reconditioned battery.
My gas mileage dropped precipitously several years ago when I replaced the original 12 volt battery with an Optima, it went from 39 mpg to 31.7 mpg. My new 12 volt battery is well within spec now too. The replacement hybrid battery seems adequate.

 

No, it decreased after I replaced the original 12 volt battery and never went back to normal.

 

The fuel economy seems pretty accurate. I'm getting what it says.

 

Well my trips are shorter so that may be part of the problem but it seems that my car is less likely to go into EV mode. My gas mileage seems more in line with a good gas powered car than a hybrid.

 

I have not had it checked by a Toyota dealer since I had some coolant warning lights and the AC and heater stopped working. They charged me a $500 diagnostic fee and told me it was a loose gas cap which proved to wrong and then told me to replace the engine, which I did only to find it was the 3 way coolant valve.
I will take it in to a Toyota hybrid specialist and have it thoroughly vetted but not for awhile, I have too many personal issues that have just come up that will take my full attention.
However I do appreciate the help and I think by modifying some of my driving I might get a few more mpg.
I will update in a few months after I get some feedback from the shop but I think the problem is more on the electrical side. My new 12 volt battery barely makes it past 12 volts (12.1 at test last time I checked) and none of the 12 volt batteries over the past 4 or 5 years have done better. I think it draws down my hybrid battery because when the battery shows a decent charge my spot mpg is at about 40 to 45 with normal driving.

 

I do have a charger for the 12 volt battery. How much can I expect if the new battery is at 12.1 volts now?

 

My last 12 volt battery lasted 5 years. My brand new 12 volt, fully charged and even now trickle charged still shows 12.1 volts at test mode and 11.8 on accessory mode.
My hybrid battery has been a concern of mine for over a year but every time I had it checked I was told yes its weak but no reason to replace it.
My tires are Michelin Defender T+H 185/65R15. They have less than 10000 miles on them and are at 33 psi.
This last week my lights lit up like a Christmas tree, just about all of them so I replaced both the 12 volt battery and the hybrid battery but my car still seems to be stuck perpetually at 31.7 mpg and has been for the last three years.