MPG All Over The Place

welcome! has all the required maintenance been done to date?

 

Your profile say's you live in Florida?

If it was many other places I might chalk it up to cooler winter weather.
But in Florida? How much cooler can it really be?

Assuming your profile is correct, I'm going to say it's not just seasonal differences.

What it could be? Sorry...but not enough real information for me to venture a guess. If it's a real problem, I'd think it will get worse and/or eventually you will get a code. Which might not be the comment you would want..or like..but any guess I would put forth would only be serving as either potentially misleading you, or planting fears you don't need...."yet".

Good Luck.

 

Welcome to PriusChat

Welcome to PriusChat! I've found that with my 2009 Gen II, I've kept accurate records of the miles driven and the gas I've used, and have found that the average over the time I've had the car (since Jan 2014) is around 46mpg. The consumption changes with the seasons since the cas companies change the formulation according to the time of year, and the area you live in, and I have logged the seasonal averages through the year, and also it's my understanding that the Gen II has a flexible bladder in the fuel tank, which might make a difference. So, I think the bottom line is not to rely on just one or two data-points, but do your analysis over a longer period of time! - hope this helps - Wil

 

a couple things to consider, low hanging fruit as it were, the health of your 12v battery, and the bladder in your gas tank.

 

im in florida as well and have had the same issues on my 05 with 172,000 miles...
no two tank fulls fill the same way, I have gone 140 miles before the gauge moved off full and I have gone 70 miles before it moves...
my advise is not to worry and fill up every 300 miles, the difference in MPG isn't a big deal, you have an old car with 200,000 miles its never going to be perfect just drive it until it drops..
when the main battery dies spend the $500 to have it rebuilt if you like the car if not dump it now but nothing is going to get you over 40 mpg unless its something a lot more expensive and newer

 

How are your calculating your MPG?

The electronic milage calculator is notoriously inaccurate, but in my experience it's pretty consistent (consistently optimistic).

Because of the bladder in the tank, the tank "size" can fluctuate with every fill up. So if you're calculating using the traditional method -- miles driven divided by gallons used -- you're not going to get consistent numbers from tank to tank. If you add the total over several tanks, then you can mathematically reduce the margin of error.

 

…to answer your question: I'm using the total volume of what I put in the tank and total distance driven, averaged over the time I've owned the car for reasons described in other posts and too tedious and boring to repeat here…

 

Sorry for the confusion Wil. My question was directed at MBurg. (I should have quoted.)

 

you're not due for plugs until 240k, but it might be worth taking a look. some things that pop up here, and aren't on the maint. schedule are throttle body and maf, pcv, intake manifold, injectors, and other. can also be you're 12v or hybrid battery going south.

 

OK, so if you're consistently getting 6-10 mpg less over several tanks , then that eliminates the inconsistent fill-ups due to erratic bladder. (The car's, not yours! )