Lifetime (or multi-tank) MPG. How to on 2004 Prius?

Manually on a spreadsheet...

 

Mine never reset itself ever?

 

The 06 - 09 don't reset the mileage. The 04 does and I'm not sure about the 05.

 

My 05 never resets unless I press "reset"

 

My 04 Never did, all manual.

 

I have an '05 with a September build date and my MFD will reset every time I fill up more than a few gallons. I always thought that all '04-05 models did this.

 

Uart, your car is doing just what we said above. The 04 and 05 reset (MPG and miles) automatically after filling the tank. The 06 - 09 only reset the miles, but not the MPG. On those model years, you have to manually reset the MPG.

 

The tripometer or the MPG?

 

My 07 resets the miles driven to 0 but leaves the mpg as is if i don't hit reset.

Didn't know this was different in other model years. You really do learn something everyday.

 

On my 04 it doesn't auto-reset. If I put gas in the car I have to press the reset button in order for it to reset.

 

My 04 resets itself, except once it didn't, that was odd.

 

My 2004 resets the MFD MPG and miles driven each time I fill up more than 4 gallons. The reset happens a minute or so after I start driving. I reset the ODOs manually (A for tank MPG and B for trip MPG) so that my lifetime MPG spreadsheet (see current data attached) gets accurate data.

JeffD

ps. The fuel GuessGuage doesn't reset for small gas fills either. It is even harder to see how much fuel is left when that happens.

 

O.K. everyone,

Maybe we're not all on the same page here. We're ONLY talking about the MPG & miles driven on the MFD screen---NOT the miles driven in the "trip A" or "trip B" display [that can be toggled back & forth with the "ODO(meter)" button].

It is my understanding that on the MFD screen on the "Classic" (2001-2003) Prius that the MPG is "lifetime MPG" & only resets if you manually reset it, however I can't say whether the "miles driven" (on the MFD) gets reset automatically (since I never owned one nor do I personally know anyone who does). I assume that "trip A" & "trip B" always have to be manually reset.

For the 2004 & 2005 models, when you add at least 3 gallons (maybe 4), an auto reset occurs of the MPG & miles driven (on the MFD screen only---NOT "trip A" or "trip B"). "Trip A" & "trip B" ALWAYS have to be manually reset. As far as to how an (MFD screen) auto reset occurs : any less fuel than 3 gallons and it won't happen [although I think I remember one time when I only put in 2 1/2 gallons & it did (but I'm not sure about that)].

And as far as to WHEN (how long after the 3 or more gallons are added) you will SEE the reset occur, there seems to be a difference of opinion here. Some say as soon as "READY" mode is achieved & others say a short distance down the road or a minute or 2 after the start of driving. But a long time back somebody stated it was supposed to happen with the first complete wheel rotation after the refueling (which I disputed at the time because it always seemed to take way longer than that for me).

I think (but I'm not sure) what happens if you refuel in the power off condition is that it takes a while for the gage to climb to the "full" reading after power up, and that may be why I was gettig a ways down the road before my auto reset would happen. I think the conditions that have to be met for the auto reset are the fuel gage to reach "full" and stabilize there and THEN the full wheel rotation. If you're an impatient person & quickly refuel, jump in & go, then you may not see the reset until the gage reaches "full", a few second delay for the stabilization, then the one wheel rotation count (& that could take a little while like I think used to happen to me).

Now when I pull in to refuel, I write down any info from the display (that I may want , if I do) & then power down (I never refuel in "READY" mode---most pumps say to "shut off engine before refueling"). I then do 2 pushes of the power button WITHOUT my foot on brake pedal to put the car in "ignition ON" condition (to display the speedometer & fuel gage). This way, as I refuel I can see through the window as the gage climbs to full.

By the time I have hung up the fuel nozzle, closed my gas cap & filler door, gotten my credit card receipt, climbed back into the car, & buckled up, the fuel gage had plenty of time to electrically stabilize & register "full" to the computer before I'm ready to push the power button the next time (this time WITH my foot on the brake---without the foot it will just shut off first & then you will have to power it up again).

With this last push of the power button (again WITH my foot on the brake), all the conditions have already been met (because the power was already on (but NOT in "ready" mode), so now as I pull ahead a few inches the car counts the wheel rotation & does the MFD auto reset right away.

For the 2006 through 2009 Priuses, all the info that I have stated for the 2004 & 2005 models should be pretty much the same EXCEPT that your MFD MPG display WON'T reset unless you manually do it (that will remain your lifetime MPG unless your kids, wife, dog, or mechanic accidentally reset it on you). But your MFD miles driven will auto reset (NOT "trip A" or "trip B" though) as long as you put 3 or more gallons of gas in.

I don't know why so many owners appreciate the "lifetime" MPG on the Priuses that have the fuel tank bladder. That can be misleading as to how far you can go on one solid or flashing "pip". Your average over the years could be really good, but you may be doing something at the present time that is using way more fuel that would allow you to run out of gas way sooner than you expected (such as climbing a long hill or mountain, driving in the rain or against a stiff headwind, or operating in extremely cold temperatures---all of which would consume more fuel & bring down your "real time" MPG for the little fuel you may have remaining in a low tank, while NOT affecting your "lifetime" MPG reading much at all).

This could lead to a false sense of security & leave you stranded somewhere remote with no gas left and you would be left wondering why you ran out so much sooner than you expected when your "lifetime" MPG was telling you how great your mileage was. But that included from maybe a few years ago when your car was newer & you had your Goodyear low rolling resistance Integrity (higher MPG but crappy traction) tires on & maybe you used to do P&G (pulse & glide) to boost your mileage as high as possible, but you no longer have the time or patience to do it any longer.

Yes, you can still look at your 6 five-minute average bars on the MFD (for the last half hour of driving only) & try to calculate how much the "real time" low MPG conditions 2 paragraphs above will impact the gas remaining in the tank, but that's difficult to do on the fly while driving. That's why I prefer to have the tank by tank average (WITH the auto reset) & to NOT ever do less than a 3-gallon refueling so the computer can always monitor the "real time" MPG & miles driven of exactly what's in that tank & display that on the MFD screen for me. I feel much more secure that way since the computer is also more accurate than writing down the old "gallons (you think you) used" (in the bladder tank?) divided into the "miles driven".

Another advantage of having the auto reset (or doing your own manual reset) is that you can more closely monitor your gas mileage of each individual tank & that could show you if something significant has recently happened that has lowered your MPG's so that a maintenance check or service might be necessary to catch something before it gets really bad. With the "lifetime" display the lower MPG's of such a condition wouldn't affect the "lifetime" display very much for some time and by then it might be too late. So my vote is for per-tank reset (be it auto or manual) of the MPG display to help keep you from getting stranded (out of gas) or to help diagnose a small problem before it becomes big & expensive.

Sorry for the long post, but it just seemed there was too much confusion about which displays were getting reset & which weren't, which model years had "auto" or "manual" resets, & how quickly the resets happen (right away at power up or a mile/minute or 2 down the road). If I've been wrong about anything in this post, please correct me. You all will be pleased to know that I can't make this post any longer by talking about the 2010 model because I know nothing about them. Talk about small blessings, huh.

Ken (in Bolton,Ct)