[ecurb]

Just finishing my first tank of gas and the MFD is showing an average of 46 MPG since pickup from the dealer. I love the car - it's like driving a video game! Here's my question. I would like to be able to see the average MPG for each trip (commute to work, trip to the store, etc.), but still have the MPG for the tank. Is it possible to have both, or must I choose one or the other?

Thanks

 

[RealAle]

You can have both, but it takes pencil, paper, and a little arithmetic. If you want your average MPG for a trip and you're a mathphob, use the reset button on the MFD and forget about having an average for the tank.

If you like math (or can stomach it for a few minutes), record your Average MPG and distance travelled from the MFD. Then go on your trip and record the same quantities again. Now do the math and you'll have your trip MPG:

Before trip: 55 MPG average, 230 miles.
After trip: 58 MPG average, 410 miles.

Here's the math, divide the trip miles by the trip gallons:

Trip miles: 410 - 230 = 180 miles
Trip gallons: ( 410 / 58 ) - ( 230 / 55 ) = 2.9 gallons
Trip MPG: 180 / 2.9 = 62.1 MPG

I'm sure a few folks have this equation programmed into an Excel spreadsheat cell.

 

[firepa63]

I am assuming that you have an 06 model. With each fill-up the 04 and 05 models reset the average MPG automatically (unless you don't put in enough fuel). With the 06 model, you have to manually reset the average MPG. Therefore, if you never reset it, the display will give you a "lifetime" MPG. If you reset it at each fill-up you will get the average MPG per tank. There is no way to get average MPG per trip unless you manually reset the MPG at the beginning of each trip, but then you lose your tank or lifetime average.

 

[DanMan32]

Sure, you could have both. Just not on the MFD. You either need paper, pen and calculator, or computer and spreadsheet software. As you probably gather, these are for recording your start miles, end miles and gallons filled. If you also record your start MPG and end MPG, you can calculate back gallons used as per the MFD. Note though, the MFD can be a little off, often on the side of being optimistic by about 2 MPG.

 

[rhackenb]

On my 2006 I always reset the MPG counter with each fillup. A few times when I went to reset it after filling up, I noticed that it seemed to have done it itself. Does this happen automatically if you refill with a certain amount of gas? Anybody know what the exact algorithm behind this is?

 

[wayneswhirld]

On my 2006 I always reset the MPG counter with each fillup. A few times when I went to reset it after filling up, I noticed that it seemed to have done it itself. Does this happen automatically if you refill with a certain amount of gas? Anybody know what the exact algorithm behind this is?

As mentioned above, that's how the '04 and '05 work. Either that's some weird anomaly or is it possible you have an '05?

 

[rhackenb]

It's a 2006 or at least the dealer said it was. That's how it's registered. Since the reset is erratic, it's very difficult to document.
I'll keep watching.

 

[PA Prius]

What? The '04 resets the average mpg automatically at fill-up? I didn't notice that. I suppose it is because I've always pushed the reset button as I've driven away from the gas station. At what point does it reset?

My wish for the world, in addition to peace in the Middle East, would be that all cars would have a mpg indicator like they now have odometers-- one that shows the lifetime mpg and two other ones which would be able to be reset. Two reset-able ones would allow us to do average tank and trip as ecurb is asking. The lifetime one would among other things show how the car has been driven. For maybe a quarter of the drivers it would also effect their driving for the better (more economical) if they allow the car to train them as so many of us Prius owners have done, also if they know it may effect the resale value of their vehicle. Any so millions of barrels of oil could be saved, and who knows, it may even effect peace in the Middle East. So much for my Sunday sermon.

PA P

 

[firepa63]

What? The '04 resets the average mpg automatically at fill-up? I didn't notice that. I suppose it is because I've always pushed the reset button as I've driven away from the gas station. At what point does it reset?

It resets within a couple of tenths of a mile, maybe less. I can't remember exactly.

 

[DanMan32]

The MPG and miles will reset once you drive a short distance and the gas guage 'sees' at least 3 gallons added to the tank. The guage takes a minute or two to completely register the additional fuel in the tank.

I don't think lifetime MPG would be ideal for manatory readouts, as once you reach a few thousand miles, the lifetime MPG would not change much, thus the driver would get little feedback to adjust his/her driving.
Heck even within a single tank, once I get over 400 miles, it is harder to reward myself with climbing MPG with more ideal driving.

 

[rhackenb]

It resets within a couple of tenths of a mile, maybe less. I can't remember exactly.

My 2006 seemed to reset sometimes after I power up (boot up?) right at the pump after filling the tank. It doesn't do this consistently. DanMan hints at an algorithm. Do you think people at the dealer know what the facts are?

 

[DanMan32]

Do you think people at the dealer know what the facts are?

Not unless they own one. I could understand dealer personnel not knowing the quirks and nuanses of the Prius any more than a doctor you rarely see know the quirks of your body better than you would.

 

[rhackenb]

Not unless they own one. I could understand dealer personnel not knowing the quirks and nuanses of the Prius any more than a doctor you rarely see know the quirks of your body better than you would.

Yeah, but the doctor should know the quirks of the body in general. The dealer should understand how the Prius works. I bet most of them don't. My dealer pointed me to one mechanic who knows more than most.

 

[wayneswhirld]

rhackenb, it's easy to confirm that you have an 06. It differentiates itself from earlier models with (among others) the HYBRID id on the front fenders, the chrome grille inset, and textured rather than smooth inner portion of dash.

 

[LittleLamb]

mpg counter reset described in '06 manual

On my 2006 I always reset the MPG counter with each fillup. A few times when I went to reset it after filling up, I noticed that it seemed to have done it itself. Does this happen automatically if you refill with a certain amount of gas? Anybody know what the exact algorithm behind this is?

I read something about this in the '06 manual that came with Little Lamb. I think it said that mpg counter resets itself automatically at each new fill up or when a certain amount of gas is added, I forget how much and I don't have the manual near me now to check.

 

[DanMan32]

Not unless they own one. I could understand dealer personnel not knowing the quirks and nuanses of the Prius any more than a doctor you rarely see know the quirks of your body better than you would.

Yeah, but the doctor should know the quirks of the body in general. The dealer should understand how the Prius works. I bet most of them don't. My dealer pointed me to one mechanic who knows more than most.

Doctors have same body model. Many doctors actually don't know certain quirks that they themselves haven't experienced, and often blow off patients' symptoms that they don't recognize, especially if it is subtle.
Bodies don't change much from generation to generation. They pretty much all have the same equipment, features and method of operation.