Prius Owners - question for you about sudden mpg drop

What if a Prius is getting 38-42mpg and then suddenly drops to getting 33mpg or less - tire pressure is ok

Any guess as to the cause of the sudden drop?

in your rearview mirror.

I've got an older one and my mileage can easily drop down to low 30's if I drive aggressively.

Though I rarely post. I think I even have DU in my profile. It's a great site for Prius info. That's where I found out about the hybrid credit from a couple years ago. I held off buying a prius for 5 months. I ended up getting a 2006 in January of 2006. I got a $3150 credit which was amazing!

Have you been running the AC non stop? The AC drains the battery. Eventually, the engine will run to replenish the battery because the AC is draining the battery.

Also, driving habits are big. Has the weather been bad a lot? This might force you to use the gas more. Have you been driving in heavy stop and go traffic? This is a nightmare for the Prius.

Those are some ideas off the top of my head.

reversible situation...thanks

If I run the AC while the car is stopped or in heavy traffic, the gas engine turns on. I try to turn off the AC if I can.

and I average 42 - 45/tank

I have no clue. We average between 52 and 54 Mpg and have never had that problem

If it was tire pressure, your tire pressure warning light would come on.

I had that happen last year, took it to the dealer ship they checked the tires to make sure it wasn't anything serious, reset the light and sent me on my way

Must be a new option - wasn't even offered when we bought ours. :shrug:

I don't think mine have ever come on. What year is your Prius? I think it changed in 2005.

neat technology but kinda scary.
http://en.wikipedia.org/wiki/Tire_pressure_monitoring_system

They have unique id's and theoretically could be used to do all sorts of nasty stuff... like call the police when you go by.. or set off a bomb... or anything else you can think of provided you can get a sensor close enough to read the thing.

"B" uses engine braking instead of regenerative braking.

a couple years back I took my car into the dealer after I'd gotten mid 30's on a couple of long trips.
The suggestion was to pick one of the big gas stations and only get gas there.
The next few tanks I only used :scared: Chevron and my mileage climbed back into the 40's.

:shrug:

A lot of gas stations are starting to stock E10 (10% ethanol) without clearly labeling it as such. Look for a small yellow "E10" sticker on the pump somewhere.

Running E10 can shave 5-10% off of your gas mileage when compared to having no ethanol blended in.

Mine will drop to around 38-42 when I have my AC on. I regularly get 50+ mpg.

A 10+ mpg drop? :wow: I've only found a 1-2 mpg drop at MOST from using AC in our Prius!

If you are stuck in traffic or lots of red lights, the battery will drain quickly.

And if the battery is drained.

As the batteries age, they tend to hold less and less electrical power, which leads to increase needs for the batteries to be charged, causing decrease mileage. If that is the case, all you can do is replace the batteries.

that is an expensive item.

From what I have read the batteries last about 3-4 years, at which point the batteries do NOT hold as much electrical power as when new. Toyota set up the Prius for a new set of Batteries after three years, but if this is the second set the owner may be trouble.

eight years. Mine's 4 years old, and I still get the same mileage or better from it. From what I hear from my buddy the Prius tech, traction battery pack replacements are very few and far between, like maybe the fingers of one hand kind of numbers. The 12V battery, on the other hand, is like a normal car battery and those will need replacement every few years.

It was (and continues to be) a major Concern when it come to Hybrids. It was the reason for the Four year Warranty, Toyota did not believe it could sell the prius without such a warranty given the deterioration rate of batteries. Thus a concern.

I only wrote of it as a potential cause of the decline in the poster's Prius, probably NOT a common problem until the car is while out of Warranty (And to my knowledge none of the Priuses are OUT of Warranty yet). While the prius has been imported into the US since 2001, the present version, the version the vast majority of people purchased and used, have only been on the market since 2004. Thus the present version being sold i only four years old, within the age range of batteries.

http://en.wikipedia.org/wiki/Toyota_Prius

The Prius owners I know typically get high 40's to low 50's.

consumption meter while I'm driving so that I use the least gas poss. I feel like I can't get a straight answer from Toyota 'cuz that's the only place certified to service the car -- they have me by the cojones

I'm hoping that if I drained the battery with my a/c last week, that the battery will recover with a few more miles of driving so that I can at least get the substandard Prius mileage I was getting.

repeated short trips so you are always only running about 5 minutes on a cold engine, then sitting for an hour or two.

We moved into town and from the valley to work, 10 minute drives, our mileage dropped off. But it does for other vehicles used for short trips too, we just don't have a computer monitoring mileage.

My good friend has the same year Prius as I and gets 60-65- she drives farther, and on flat terrain. Same island, same gas, same maintenance, different routes.

Oh and we have flippin ethanol in all the gas here. grrr.

Lot's of stop and go driving on LI. I usually get around 45MPG on steady HW driving.

if this loss in mileage happened in a relatively short time. batteries do go bad even the ones in a Prius can.

http://www.hybridcars.com/gas-saving-tips/maximizing-mileage-toyota-prius.html

Also note: refueling should be in the coolest part of the day and VERY slowly inputting the gas.

I usually get in the high 40's around town and and just over 50 on long trips.

In a 2007 touring model. I keep a spreadsheet and have only gotten better than 40 on a couple occasions. Got 51 once but was probably a math error.

I usually drive anyway I want, meaning 80-85 on I-5 and other major freeways or in the country, so I'm not expecting 40s and 50s.

However, I've tried hypermiling and it's not much better.

I believe that some just get better mileage than others. Period. I don't know why but it seems that older ones do better.

I just got new tires and am going to try higher pressures just for kicks, after reading this:

Drivers getting the highest mileage recommend using the recommended maximum tire pressure on the sidewalls—not the psi supplied by the automaker on the doorframe.

http://www.hybridcars.com/gas-saving-tips/maximizing-mileage-toyota-prius.html

The door plate says 35 psi, tires say 51 psi, I'm going to try 45 psi and see if there's a noticeable difference.

I have a 1st gen and when I got it the tires were at the factory recommended 32psi.
The tires are rated to I think 46(?) so I put them at 40/42 and my mileage instantly and dramatically improved.

Hard to say until I've driven more, but I did some 4 mile flat road runs yesterday at different speeds, got 64.5 at a constant 45 mph and about 52 on a mixed driving 12 miles.

Car sticker says 35psi, tires say 51 max, I inflated to 45.

the mpg seems to be back to the normal range for this vehicle - I used the a/c very judiciously and did the pulse-pump granny driving -- so I think it was extreme overuse of a/c while the car sat idling that knocked it out for a few days

thanks to everyone for their input

diva