Save the world, lose a marriage?

[Screaming Red]

Greetings all, from newbie '07 owners - still on our first tank and getting around 42 MPG. Here is the problem:each of us is maneuvering to claim the honor of achieving the highest mpg/trip, and when the alternate driver starts up the car, the trip computer registers 0.1 to 0.2 mpg less than the earlier user saw at the end of their trip.

So I climb out convinced that I "nursed" her up to 42, and Himself says, "Oh no, you only got it to 41.8 - that 's what the computer showed when I got in. Can anyone solve this gentle rivalry? Is it usual for the computer to adjust downward when the car is restarted?

[Godiva]

Have you been hitting the reset button when each driver changes?

You need to reset one of the trip buttons and then reset the consumption each time you change drivers.

[Dan.]

<div class='quotetop'>QUOTE(screaming red @ Apr 4 2007, 12:45 AM) [snapback]417488[/snapback]</div>

Greetings all, from newbie '07 owners - still on our first tank and getting around 42 MPG. Here is the problem:each of us is maneuvering to claim the honor of achieving the highest mpg/trip, and when the alternate driver starts up the car, the trip computer registers 0.1 to 0.2 mpg less than the earlier user saw at the end of their trip.

So I climb out convinced that I "nursed" her up to 42, and Himself says, "Oh no, you only got it to 41.8 - that 's what the computer showed when I got in. Can anyone solve this gentle rivalry? Is it usual for the computer to adjust downward when the car is restarted?
[/b]

Yes, when you get in the car and start it, for the first 5 minutes you'll get in the 20's for mpg so your average will always go down when you start it, and nurse back up while you drive.

If your comfortable with a little math there is an equation you can use use to calculate the "trip" mpg without resetting the tank mpg. Here's how it works. Write down the miles (tank) and MPG at the start and end of each trip. You can calculate how many gallons of the tank you've burned by miles/mpg.

So to get your trip MPG you simply determine how much gas was burned before and after your trip, assuming you know the miles driven, now you have your miles and gallons to calculate miles per gallons.

The equation is as follows.

Given:
Gallons_Burned_From_Tank = Tank_Miles/Tank_MPG
MPG = Miles_Driven/Gallons_Consumed
Gallons_Consumed = Gallons_Burned_From_Tank_end - Gallons_Burned_From_Tank_start.

therefore:
MPG_Trip = mi_Trip / (mi_tank_end/MPG_tank_end - mi_tank_start/MPG_tank_start)

Clear as Mud? Try plugging it in to excel and you should get good results. It will also give you a nice trip log so you can tell if your MPG is improving over time.

11011011

[Ichabod]

It's always going to be a little imperfect, even with Dan's method of figuring trip MPG. That will be close, but really the only way to do it right is to buy a second Prius

[hill]

When you get REAL good at doing the mileage thingie with practice, you can get your 1st Five minutes of driviving up into the 40mpg's ... and THAT's what really raises your average ... expecially on those short 10-15 minute trips.

[daronspicher]

I think in california there is a checkbox on the divorce decree...

"Can not agree on Prius MPG accomplishment"...

Sorry you're from Idaho, you're just going to have to live with this....

[dmckinstry]

<div class='quotetop'>QUOTE(Ichabod @ Apr 4 2007, 07:17 AM) [snapback]417551[/snapback]</div>

It's always going to be a little imperfect, even with Dan's method of figuring trip MPG. That will be close, but really the only way to do it right is to buy a second Prius
[/b]

Yes. But then to be really fair, you'll have to trade off with your wife every once in awhile so she can't claim you have the "better" car.

Dave M.

[Rangerdavid]

<div class='quotetop'>QUOTE(Dan. @ Apr 4 2007, 08:28 AM) [snapback]417533[/snapback]</div>

Yes, when you get in the car and start it, for the first 5 minutes you'll get in the 20's for mpg so your average will always go down when you start it, and nurse back up while you drive.
[/b]

The first 5 minute bar is basically the "warm up period". Hence the increase in mileage with the block heater. It warms up the car before you get in and drive, so the first bar goes up from the 20-25 range to 40-45 range. My mileage went up a great deal since my EBH install.

Also, time and experience driving the car are invaluable assets. I've been experimenting with alternate routes to and from work to try and find the one with the best mileage.

[Screaming Red]

<div class='quotetop'>QUOTE(Ichabod @ Apr 4 2007, 10:17 AM) [snapback]417551[/snapback]</div>

It's always going to be a little imperfect, even with Dan's method of figuring trip MPG. That will be close, but really the only way to do it right is to buy a second Prius
[/b]

[Screaming Red]

Dan's equations were a bit much, even for these two enginerds. Think I'll stick with the old and simple miles/gallons formula -- taken out 10 decimal places for accuracy. (43.9 mpg at fillup today, WahOO.)

Rangerdan, that makes perfect sense, that startup would drop the mileage, and I'll try hill's suggestion to work the mpg's early in the trip. Love that onboard video game.

Ichabod's reply is right on, we need two Prii. (Priuses?) Especially since I want white and had to 'settle' for screaming red.

To daronspicher, Idaho is a bedroom community for CA.

Thanks, for the warm welcome, all!