MPG avrg too high.. way too high

I assume you've had this car for several years. Do you reset the MFD each time you fill the tank? Do you keep records of these fills (other than the past three)?

There are two issues I'm after. The first is that the 42 you see could be for a longer term than your other (3 tank) measure, unless you've been resetting the screen. The second is that you really cannot get a good idea of the mileage (separate from the MFD info) unless and until you record many, many tanks.

 

Have you checked your tire pressures lately? Has it been colder than normal in your area?

 

Yes, it should display the correct MPGs. I think part of the problem may be an assumption on your part that the calculations from two or three back-to-back tanks will give you more accurate data. The bladder is going to make it nearly impossible to get such measurements to be accurate over a short term.

Any sudden drop in mileage is a real and valid concern. It could be related to tire pressure -- even that significant a drop. It also could be a problem with your brakes, or it could be failure of a sensor in the emissions system. I would first recalculate your numbers (cheaper than anything else), then start with the tires. After that, make certain your air filter is clean. If all checks out, then consider whether weather changes or changes in your driving habits could be involved. If all this fails, then set up an appointment with your Toyota mechanic.

 

I would think the MFD should display the correct mileage, even if it has dropped for some reason. Are you sure no one is siphoning gas from your tank

 

Your issue is the inconsistent nature of the fuel bladder. I would be more worried that you are only getting 42 mpg.

... Brad

 

Miles, gallons, MPG. No matter if the mileage is down or not, it should register it correctly on the screen

 

Perhaps you might try one of the online mileage databases. This makes tracking long term trends much easier. Although I prefer myhybridcar.com, there are others including one at ecomodder.com. By recording your mileage over time, we'll have access to the same data and perhaps get a clue about what is going on. For example, this is my data.

GOOD LUCK!
Bob Wilson

 

When you see hoof prints think horses, not zebras. Whenever there's a sudden change in MPG, check the tires first.

 

There are several factors in low mpg. Things you can change are:

1) Proper tire pressure
2) Ensure that oil is not overfilled
3) Speed you drive (faster = lower mpg ie 75mph vs. 60 mph)

Other factors (wind, short vs. long commute, outside temp-lower temp = lower mpg) are factors you cannot change. Short trips really kill the mileage.

Best of luck.

 

Can I humbly add a fourth...
4) The way you drive

Its an instrument with only two pedals, but how you play them can make a huge difference to the music!

Getting back to topic, I would agree that the MFD should be correct. Mine doesn't have a fuel bladder and the fit between measurement methods is almost perfect.

 

this site has had a million "mileage" threads so i will go over key points.

you should track all your mileage all the time. besides validating the display, its a great indicator of possible issues with your car or the accuracy of the pumps you are using (an estimated 10-12% are ripping you off btw...)

when your mileage drops, check

tire pressures
changes in gas stations for pump accuracy
overfills on oil changes or any recent maintenance issues

and MOST importantly and what i think your issue is especially with the miles you are driving is changing your engine air filter.

now, none of these things would cause a major discrepancy in the MFD display but will cause a drop in mileage other than gas pump rip offs.

as far as blame, its very unlikely that the MFD reading is significantly off. all realistic measuring devices have some error. however i would always take the MFD as more accurate than any gas pump

 

The only time I have seen the in car indicated consumption much higher than the actual took me a while to work out, it turned out to be a small leak at the bottom of the fuel tank, this is not mesured by the MFD so that would show consumption without the leak. Over time a few drips can make a big difference to consumption.

 

I was waiting for someone to mention the possibiltiy of a feul leak. Since gas is very volatile, you likely would not notice any puddle under the car with a slow leak as the feul may evaporate almost as quickly as it leaks out. You might have more luck smelling for it.

Or, they may be a fault in the feul injection system that is also influencing the way it measures the feul flow.

 

Can the door be opened from the outside without tell tale signs?

 

What is your driving style? If you are driving 70 mph on your commute your not going to get the 55 mpg your might achieve at a more conservative 45-55mph.

I usually will drive about 62mph on the expressway and in the summer I average 54 mpg. If I take a slower road and cruise around 45-52 mph I find my averages can rise to 58 mpg. Those days that I run late and need to go 70 it does cut back to 49mph.
(I have a 2005 with 15000 mile on my GY Comfort treads.)

 

The calculation is based off of what you're reading off of the pump right? Not what you think the car takes in fuel?

I whammed the fuel tank a while back on a smooth curb at a weird angle - and there is a huge dent in it - which dropped my tank capacity quite a bit, it signals at about 8 gallons now and I am dry at just short of 10 - instead of 12.5 - so I only go like 400 miles where I was clearing 5 before -