Significant MPG loss at 50,000 miles - HELP!

50,000 miles is early for a brake replacement. Most Prius will make it 100,000 miles on the brakes. Are you sure your brakes aren't dragging?

Tom

 

Cycle your emergency brake a few times, check your oil- 2/3rd's up the dipstick is optimum, check your air pressure the dealer would have set it back to factory specs.
Possibly a bad spark plug or a bad connection, a 20% decrees in mpg is unacceptable

 

Get your 12v battery checked. After 3 years it could be starting to lose charge. When that happens, the engine runs more and more in an attempt to keep it charged, thus losing mpg.

 

Amazingly, dealers do not always check the battery correctly. You can do it yourself with no tools using this procedure:
http://priuschat.com/forums/newbie-forum/73400-weird-stuff-happening-mpgs-dropping-test-battery.html

 

Since you have 50K miles, you're might've changed your tires. If so, please specify what you have. Yes, the other things are good to check everyone else has pointed out are good things to check. Otherwise have suggested also checking the mass air flow sensor.

I wouldn't have thrown $ at the spark plugs (they changed WAY early) and am unclear about the brakes as they shouldn't be worn at that mileage.

Although I don't think you need to fill out http://priuschat.com/forums/gen-ii-...-answer-these-questions-esp-if-youre-new.html, there are few points there that you might want to check/answer.

Some of your drop is likely colder weather and winter blend gas, I don't think all of it is due to that... and I hear that the LA area has been occasionally getting some pretty warm weather.

I think a decent test is to go on the have the car warmed up, go on the freeway when there's no traffic (yeah yeah, tough in LA) and set the cruise control for some reasonable speed (say 60-70 mph), drive for a couple miles and come back the other direction (to help cancel out wind effects) and report your speed, outside air temp, and MFD's indicated mpg.

Please do this after checking your oil level, tire pressure and 12 V batt voltage.

 

It might could be the MPG reduction is due to a dirty MAF sensor.

More info here.

 

After you check all the items mentioned by others, you will come to find what many, including myself, have found....there are no answers for why this happens.

 

how about checking something as simple as the air filter, and dumping in a bottle of chevron fuel injection cleaner. The costco's on willow near you has 6 bottles for 15.

 

. . . . . or check your tire pressures (make certain at a minimum they're in the 40lb range). or maybe it's just bad gas.

 

If you regularly buy gasoline with ethanol in it (and who doesn't) the engine is already getting all the injector cleaner it needs.

Did *anything* else change just before you noticed the MPG drop? New driver? Different commute route? Extra rider in your car pool? Started carrying your surfboard as a roof ornament?

 

This has happened to me too! I've taken my car in twice to get it checked out and each time they treat me like I am crazy. Were you able to resolve the problem with any of the suggestions given here? The 12V battery test sounds good.

 

I purchased a used 2007 Prius last year. When I checked my milage, I went from 36 miles per gallon down to 27 miles per gallon by the third tank.
.
I took it in to the dealer and insisted something was wrong. They kept telling me I didn't know how to drive it correctly or I have been putting in bad gas. I insisted something was wrong and they insisted after looking at it, nothing was wrong. The next day when I went out to start the car, It was dead dead dead. Had to have it towed into dealership.

They put a new battery in, and as I drove away I saw my milage on the screen jump to 47 (never went over 37 before) Now my gas milage is over 40, so my guess it is your battery.

 

What were you getting before and after? What conditions changed, including your commute, weather, oil, tires, etc.?

If you want fuel economy help, please start a new thread and answer the questions at Fuel economy complaints/queries? Please copy, paste & answer these questions, esp. if you're new.

 

I can't help you but since you mentioned 35-36 mpg, I am embarrassed to admit this, but thats what I have been getting since I bought my car new in '07. I was told over and over that it is because I live on a hill or the bad conditions of the streets. I accepted their answer. I love my Prius but this is absurb. Another Prius owner said my car cycles too much. After I brought it in, the dealer said, no its fine. I just joined the group, can you tell?

 

I'll say it again, if you want fuel economy help, please start a new thread and answer the questions at Fuel economy complaints/queries? Please copy, paste & answer these questions, esp. if you're new.

It may be normal for your conditions, how you drive and your length of trips, but there are many things you can do and check first.

See ConsumerReports.org - Most fuel-efficient cars for what Consumer Reports got in their testing of the 2nd gen Prius, which is what yours is.

 

Deleted

 

Hello from Anita. I am a Newbie on this site.
I have just read the above discussion and comments about the sudden reduction of MPG. I am at this moment sitting in the waiting room of my local Toyota dealer after being told there is nothing wrong with my my 2008 Prius; I have had a sudden reduction of my MPG from 44.5 to 33.5 after having the 12V batter jumped when I left an interior light on.
I have done the suggestions here myself and the dealer also did them along with some other tests. When I pressed the "Vehicle Signal Check" while in Maintenance mode, I got a reading of 11.6 volts (the note here says it should be 12.4-12.8) The dealer said that when they did this it went up while sitting in this mode. They also did some test when there was a reading of 450 (I forgot what reading this is) and that meant that the battery was fine.
They ran the car through a bunch of other tests and pronounce to me that "We cannot find anything wrong". My service rep said that he and the head tec were putting a "claim ticket" in to Toyota with the complaint so that if there enough complaints like this then maybe there will be some investigation. (my interpretation, not a quote)
I am on the verge of tears, I have to tell everyone. I have had my Prius for 2 1/2 years and feel very disappointed. Any more help or feedback is greatly appreciated.
Anita
Oops, my car has 40,000 miles!