Hit a new low in mpg

There's someone stealing your gas

 

have you checked your 12v health. what are your historical mpg averages?

 

If you can post answers here to as much of this questionnaire as practical, it will give us more clues to guide feedback:
Fuel economy complaints/queries? Please copy, paste & answer these questions, esp. if you're new | PriusChat

Another subject not covered in that questionnaire, but which has been popping up more frequently, is brake drag from frozen or sticking calipers.

 

good point, especially 2010's.

 

Could be a combination of several things; tire pressure, brake drag, more a/c use, poor gas, etc

 

Tank distances are not very useful to use us because 'tank' means such vastly different things to different people. MPG, either from the display or calculated from the refills, is far more useful.

???
Are they inflated to 40, or to the maximum number listed on the sidewall? I don't recall any common tires with a 40 psi max stamped in the sidewall, most that we deal with show 44 or 51.

Are the tires original, or new, or replacements that have already rolled more than a couple thousand miles?

Again, actual numbers please, along with how long since the car was turned off before making the voltage measurement. 'Normal' has too many meanings, and too many shops have reported batteries as being good when they really were not.

The car could be 6 years old now, so an original 12V battery would be a suspect. Some would still be OK, but many are already dead or dying.

You could save a bit by pushing the fan speed down, and the temperature up, and likely still find adequate comfort. But this could comprise only a small part of your MPG shortfall.

You should have switched to 'B', not driven down it in 'D'.

Can you give us actual speed numbers? 'Flow of traffic' means vastly different speeds in different regions.

 

how many miles on her? the warped rotors thing is concerning.

 

Jon, did you get the software update, to better protect the inverter? There was a recall notice.

Some owners reported significant mpg drop after the update. Others none. Personally our mpg seemed to improve slightly, post update. Seems a crap shoot, with some owners losing.

 

That easily rules out the new tire break-in issue, where new tires reduce mpg a bit until they are broken in.

Do you have a voltmeter to measure the battery, after the car has been sitting off for at least a few hours, and before re-starting it?

While aged 12V batteries are a common issue, they are not always part of the problem, some are still good enough at that age. Thus, some folks have replaced it and gained nothing. So it would be useful to get a reading before blindly shotgunning the battery, unless you are ready to just replace it anyway.

I hadn't looked back at your first post as a reminder, so missed the mpg number.

 

OK, sounds like you've covered most bases (the warp rotors might be culprit) but before attributing it solely to the car, we should try and see if it's the driver and a change in driving habits. So, I'd suggest you top off the tank, give it your best attempt at hypermiling kung fu and report back.

 

some people start having fuel issues, throttle body, injectors and etc., so, you've got a pretty long list of things to check out. start with the easiest, and work your way up. all the best.

 

See if any wheels feel hot, after extended drive.

 

I'm curious whether a new ECU I had installed could be causing low mpg due to not being calibrated correctly? I

have a very confusing situation with my 2006 Gen 2 Prius:
- 3 month ago Hybrid battery failed, and I had to pay to have a brand new one installed
-Toyota also installed a new ECU
- first week, shot up to about 44 mpg
- Suddenly a few weeks later, plummeted to 27 mpg. I was driving the exact same routes in the exact same manner.
- Toyota dealer did a diagnostic check on battery and claimed everything was fine.
-Thanks to the priuschat forum, I noticed that people said when 12v battery is dying they saw a sudden major drop in mpg. I used a simple test and discovered that my 12v battery was indeed shot, which made sense because it was about 5 years old.
-I replaced the 12v battery
- Mileage immediately jumped up to around 40 mpg.
-But again, about a week later it plummeted to 32 mpg. Strangely, my MPG meter on the display jumped around like crazy, even when I drove steady.This is exactly what it did when the HV battery died.
- I noticed that in the city, when accelerating power is very weak and the gas engine is always running at 100% without any assiatance from the HV battery. On the highway, mileage seems to be ok, in the low 40s. But again, when accelerating or driving lower speeds in the city, it is struggling and powered only by the gas engine.
-Lastly, HV Battery meter that shows bars to indicate charge, never, ever, reaches a full charge. It's always 3 or 4 bars short. Correct tire pressure, not running AC or high heat.

I'm wondering if any of these might be the culprit:
- When Toyota replaced ECU they didn't update software or calibrate it correctly
- When I removed the old 12v battery and installed new one, it caused ECU to lose correct codes/calibration
-Toyota gave me a defective ECU
-

Any advice is appreciated!

 

Just to add to your list of possible culprits:

- The new battery is marginal/defective? Say due to sitting in storage too long, or whatever? Or (a little paranoid) because it was actually used, or returned, something like that?