weird mileage concerns

sorry see nothing wrong with your stats. dont worry about individual tanks. keep lifetime stats and base your driving on a combination of what you normally average, current MFD reading for your tank, and the bars you have left on the gauge.

also, although, not certain (there is a lot of posts that mention it though) when going through major temperature changes, the capacity seems to change too. most seem to get less capacity in their tanks as the temps drop. couple that with the move to winter formula gas (which has less gas in each gallon) and tank averages will be dramatically different

 

Bought our Prius in early August and haven't noticed any problems when filling her gas tank. However, we don't keep close tabs on tank mileages and just refill whenever there are only two "boxes" lit on the fuel indicator.

Some have notice fuel bladder issues and discussed them on this site.

We haven't noticed any problems with back pressure while fueling up, but there have been reports of such.

 

I have to agree with just worry about lifetime mpg not tankful.

The amount of fill has to do with the bladder in the tank.

You can not keep short term accurate measurements when the tank does not fill to the same point every time.

My last fillup... 2 bars left... took only 6.6 gallons.

I didn't think at the time after the pump clicked to put it on slow or medium until it clicked again. I just paid and left .

I then thought she must have not taken a full tank...but it was weird because the tank read full and the first bar did not disappear until around 120 miles... she always does this.

 

As with others I only fill up when the last cell is blinking. I only put in 10.0 gallons. This minimizes fuel stops and makes calculating cumulative fuel efficiency very easy. I keep track using Excel and keep a current paper copy in the glove compartment (handy for sharing with nonPrius owners when there are questions). While knowing the current tank fuel efficiency is nice, place your emphasis on the cumulative or long-term fuel economy. You will have a much better sense of the health and performance of your Prius.

I too become concerned when a single tank fuel economy decreases. When I fill up again, the cumulative fuel economy puts things in long-term perspective. On occasion, due to traffic and road conditions, I cannot drive in my normal frugal manner. When I take a "hit" I work diligently on the next tank to protect the cumulative fuel efficiency.

 

Bloomfield Hills MI hmm. What has the weather been like? I no longer live in the Midwest but in a more temperate climate but we are clearly into the fall/winter season (not much difference between either fall/winter or spring for that matter) the temps are down and as I have the Scan Gage, so I can track the engine temps, I am now very aware of how much longer it takes for the car to get up to the temp to be in full hybrid mode. In my am commute it takes about .5 to .75 more miles to get at full hybrid mode at 50 F. It is going to get worse when we are in the mid 40's. I grew up in Ohio and went to school in Hillsdale MI. It is going to get much colder where you are! Your milage will drop. The Prius is about reducing emissions. That is "job one" for the Prius. It is going to keep the car and the catalytic converter at optimal temperatures, if you want a bit of heat for your self it will cost you!!! Getting the car up to temp will burn fuel just to heat it up. Wait till summer you will do far better than me! My summer temps are in the mid 70's for the highs! 50's to low 60's in the am. I will never get the m.p.g. you will in the summer. It is a give and take imagine the hit folks it Alaska and Canada take in the winter!