Can toyota modify MFD mileage calcs?

Check the oil, its been reported that an overfill reduces milage.

 

did they rotate tires? may be secondary tire break-in.

 

its the temp change. 20º is more than enough to change a few miles or so. one thing i found it that the hotter it is, the better the mileage if all else is equal. usually most, especially people in your area, wouldnt notice because the air would negate any major differences.

keep in mind that if your commute is long, the difference wont be as much, since temps are only going to affect the first 5 mins of driving.

i drive an 8.8 mile commute. this past summer i would drive in the morning and lose +/- .1-.2 mpg on my tank. in the evening, i would gain .2-.3 mpg. no elevation changes to speak of, only difference was that my car in the evening would still be very warm from the heat of the day. (i got off work at 7-8 pm...sun doesnt set till 9-10 pm) didnt use air 90% of the time because i prefered the down window thing. (commute speeds never exceed 40 mph) so even with the loss of aerodynamics from the down windows, my mileage still improved.

so yes, temp plays a huge roll... in some cases.

 

Hey Gang,

I think everyone has missed the point. His actual calculated mileage has NOT changed. Just the readout on the MFD. IF he had 50mpg on the MFD on most fill ups prior to service, it sounds like it's now reading 47 or something lower.

Eitherway, it sounds like whatever caused the change, has just helped since it's made your MFD more reliable.

 

i understand what he is saying and i went through the same thing last year. another thing you might want to look at is the mileage you now have. when i first got my Prius, the MFD was consistantly 1-2 mpg higher on the average. as time went by, the difference became smaller. the bladder stretching a little bit would cause this right? so i accepted this.

but then right at this time last year, same mileage (well actually about 8,000 on mine) boom, the difference bet the two readings started to shrink and that can only partially be due to the bladder's not expanding anymore. so then you look at other changing factors and temp was the only measurable variable that i could see also...

now is this conclusive? after another year, the difference is now that my tank mileage has swapped places with the MFD mileage but the change has slowed considerably. but will have to wait out another winter to see what trends develope... too early yet.

the other thing i can say to this...if this aint the right answer then you need to

DUMP YOUR DEALER!!

if he is performing maintainence behind your back, get out while you can'!! i dont care what the procedure is or how critical it is. if someone does something to my car without telling me about it first, it will be for the last time

also, i really think you simply need more data before any real conclusions can be made.

 

It stands to reason that there are coefficients in the onboard computer that will affect the accuracy of the MFD milage calculation. The Prius is offered with several different tire combinations in other geographies, for example. The MFD milage calculation needs to know the outer diameter of the tire for its distance calculation, so an incorrect setting would cause errors in the reported milage. There could be other internal settings which also affect this number. Sounds like the dealer may have caught an error and fixed it.

 

I think that's also possible. Where I live the temps have gone from 70s to 40s and I've noticed that the bladder behaves differently at fill-up time. The question is whether the car compares miles driven to the quantity of gas in the tank, or to fuel flow (or both).

 

The essense of your post is correct, but the vast majority of Prii (North American, European, and the base level of the Japanese domestic model) ship with tires that have 852 to 855 revolutions per mile (on both 15' and 16' rims).

Edit: the Aus/NZ model comes with a 195/60/15 @ 862 revs/mile - still close enough that I doubt the speedo/odo etc are recalibrated.

 

i guess we need some input from one of the Toyota guys here.

would you ever perform an upgrade and not tell the customer before or after the fact?

Toyota (like all companies!!) puts a lot of emphasis on their CSTS (Customer Service Transactional Survey) scores and one of the questions is

I]What did the business do to distinguish their service from the competition?

i cant imagine any service center doing an extra service for the customer and not telling them. imm, doing it first without informing the customer is poor business practice, doing it and not telling the customer after the fact is criminal

 

hmmm seems to me this would assume a different way of measuring distance when calculating the mileage. if the distance used is taken from the odometer for both methods of deternining mileage, then the tire differences would be negated

 

I always let my writer know if I find an outstanding recall that hasn't been completed. That would be the only time the Prius would have been reflashed. There is also no other changes I could make to effect the concern that has shown up with HybridVigor's Prius. So to answer your question,Dave,I wouldn't do anything that the customer didn't ask for till I had let them know what it needed.

 

I find it interesting to compare the information I get from the MFD and the ScanGage. The ScanGage reads slightly higher than the MFD and closer than my calculated. This must be tempered by the fact the fill ups are not totally consistently. I think that the MFD is an approximating of the true MPG. Keep records the life time mpg is the best measurement of performance.

 

Strange, my manual calculations are almost always lower than the MFD's by 1-2% (15,000 miles, ~30 fill ups, only in two were my calculations higher than the car's display).

 

Vigor,

Open the hood of the car. You've probably got mynoks chewing on your power cables.

 

I had my acces bat. changed and so far had two 75mpg bars with suburban driving. This is the first time in 11 months that Iv had such astounding readings ( not first bar, of course). That 12 volts feeds the MFD.