We've had our new EHV for about 3 weeks and, of course, we're watching the mpg with fascination. We have a 2001 Prius, so it's fascinating only because it's an SUV, not because it's a hybrid.

My husband and I had a "discussion" the other day about the FE screen - I want to get a sense of the MPG by getting some mileage under our belts; he wants to reset often to get data points of shorter duration. I'm winning so far because it's "my" car and he won't reset it unless I give the okay. We have a little less than 1000 miles on it. I don't intend to *never* reset it, I just want to accrue more mileage first (I'm not sure what that reset mileage marker would be... )

I have two questions really:
1. Does it matter which way we do it?

2. I'd like to enter my Escape into the database here - are people entering gross mileage data or trip-by-trip data? It looks like the latter. I'm willing to do either - just need a little giudance.
Thanks -
Kristi

 

I'm putting data in tank by tank. I've been calculating mileage based on miles divided by gallons and comparing that with the number from the computer. They are not quite the same but I expect they will average out over time...

 

Kristi,
Most people are going tank-by-tank and adding it to the database. I'm not familiar with how the Escape is set up, so perhaps you can enlighten me. Is there only a single fuel economy figure? Does it automatically reset when you fill up? The Hondas are equipped with trip mileages, as well, but apparently the Ford is not?

Keep in mind that the more often you reset, the less accurate your figure will be when you average it all out. Think about the significance of the rounding if you're resetting every 10 miles.

 

Thanks, Steve and Jason - I'll try the tank-by-tank method.

Steve - Do you reset the Average FE guage each time you fill up? What do you think so far about the Escape vs the Prius? ...although it's probably an apples/oranges comparison since they're such different vehicles.

Jason - the FE screen in the Escape gives a bar that displays instantaneous FE, a histogram that displays FE over the last 15 minutes -- the newest minute of data shows up on the left side of the graph while old data falls off the right side, (this seems oddly backwards to me) and then the Average FE is displayed in the center of it all - this is the data I'm most interested in. It does not reset with each tank of gas but can be reset manually at any time.

 

Yes, I reset at each fillup in both cars. While the Escape and the Prius are different feeling cars, the similarities in the hybrid system mean they drive very much alike...especially the "classic" Prius which is what we have.

The FE screen in the Escape seems backwards to you because it's setup the opposite of the Prius screen. I'm sure if you'd had the Escape first you would feel the same about the Prius'.

 

Hi, Kristi... I don't have a Prius or an Escape, but I'll tell you how I use the GH db to accentuate how I keep track of mine...

I use the GH figure as a 'total lifetime FE' stat. It's got every one of my gals / miles / mpg's up there, so as long as the calculated average is 'total miles / total gallons', I'm ok (Jason, if it's avg added to total avg, let me know - and please consider changing it, because the number will be skewed badly if it's 'avg' and not 'total') I believe that I did check this the first couple of tanks and it jived, so I think we're ok

Since 'lifetime' has now been taken care of, I have 3 other measuring devices left - Trip A, Trip B, and the instantaneous (which I configure to reset on refill). I use Trip B for any trip I like, regardless of duration. I usually calc my 'to work' MPG, my 'from work' mpg, and then on weekends, I keep track for the day. I'll also use it to demo to friends who ride in the car.

Trip A then becomes my 'tank' mpg. It's not foolproof - the most accurate is always mi / gal, as indicated by your odo and gas receipt, and that's what I report - but it's a good indicator, and lately, I've noticed that it's not off by more than about 0.2mpg from actual.

Now, because I'm *truly* ****-retentive (enough to know that that word is hyphenated... ) , I also record actual / trip A / instantaneous in the 'calendar / memo' portion of my navi unit. Can't tell you the purpose it serves, other than having history readily available, but it's there for the future. I do not calc or keep the lifetime avg in there, though - that exists only on GH, although I could reconstruct it if Jason lost his server data, etc

I believe some folks with the dual trips leave one for a perpetual, and only reset the other. I tried that for a couple of tanks, but...
a. Realized I'd lose my 'tank avg' (the most accurate one, anyway, compared to the instantaneous avg)
b. Realized that I'd have no easy way to see total tank miles (again, Trip A / B are more accurate than the Instant.)
c. Thought: "what happens when someone resets it, either accidentally, or through having the car serviced, etc..." I can see myself having a coronary over that, in direct correlation to the number of miles travelled w/o reset, and it's not worth it.

So I reset A/B on every fillup, leave A for the 'tank', and B for whatever I choose, and let GH calculate the lifetime. Seems to work for me

 

Actually, because of how most of us record mileage, odometer/gallons will not be the most accurate method of determining lifetime fuel economy; distance and gallons are not the requested inputs! Rather, distance and mileage. If I convert to gallons and then use gallons in the lifetime calculation, it's inaccurate. Therefore, I weight the tanks' mileage based on distance for that tank, add them all up, and divide by the total [edit]distance[/edit].

Yes, there is a "gallons" input. It was an add-on feature, and that value is converted to miles when it's stored. It doesn't really lose accuracy, however, as people usually will input gallons to 3 decimal places but mileage to simply 1 and miles to 0.

 

Ok - I'll start by saying that I *trust* your data, because you've got a lot more data & community of users than I have experience (you're probably better at math / statistics than I am, too). But I'd like to *understand* (and I guess this is an aptly named thread to have this discussion

We state that distance and mileage are optimal. But - isn't mileage determined by distance / gallons ? Otherwise, the only way I see to get it is to report from the trip odo ?

I took interest in your statement "because of how most of us record mileage" - because the only way that I ever knew (20yrs or more ?) was to:

read distance (a) on fillup
drive
read distance (b) on fillup
subtract a from b for distance travelled on tank
get gals needed to fillup (c)
(b-a) / c = tank mpg

If someone can explain my error here, relative to Jason's response, and then I'll ask another question once we have this part out of the way ? Thanks!
PS: I'm signing off for the night, but appreciate any responses / willingness to keep this going tomorrow

 

Haha, my apologies. I know I didn't explain that very well... kind of typing away frantically without being clear.

Miles: 100, 200, 150
Gallons: 2, 4, 3
Mileage: 50, 50, 50

Your method: (100+200+150)/(2+4+3) = 450/9 = 50 MPG
You only use miles and gallons.

However, the hybrid displays only tell you the mileage for each tank (usually). At least, that's how most of us report it. So, this is what I do:

[50(100)+50(200)+50(150)]/(100+200+150) = (5,000+10,000+7,500)/450 = 50 MPG
I only use miles and mileage.

 

Isn't it the same thing? Your calculating using miles and mileage, but to get mileage, you need to use miles and gallons, so you're essentially using miles and miles and gallons.

The proof that gallons is in there, is that your final figure is measured as MPG, miles per gallon.

Or am I missing something?