'98 Chevy Metro

[TooMuchGlass]

Awesome everyone! I got my Scangauge rocking, and I got 49.7 on the ~8 mile trip to work this morning (I think there are 7 traffic lights). I could hardly believe it! It sounds too high, honestly, but Saturday I got about 45 on the same trip, and that was with 2 175 pound buddies in the car.

Are these numbers a little too optimistic? I mean I have ~33 psi I the tires and while I am practicing good driving techniques, I'm not doing any EOCENE or anything. And I got ~42 on the way home, so it isn't like the whole drive is downhill.

[MetroMPG]

Only way to know for sure is when you fill up.

Mine reads about 7-8% optimistic on fuel use, if I recall.

[doviatt]

Keep up the excitement and focus on these little trips. This is how you improve. The whole tank result will be you final measure but the intermediate gains can keep you going.
Nice job.

[TooMuchGlass]

Got about half a tank, so I'm planning on filling up tomorrow before a big trip on Friday.

This will be the first fill up with the ScanGauge.

[TooMuchGlass]

Got about half a tank, so I'm planning on filling up tomorrow before a big trip on Friday.

This will be the first fill up with the ScanGauge.

[doviatt]

It took me a few tanks to get the calibration just right. Either way.... The tank data is king. That is your actual number regardless of what any instrumentation says which is why it is better to run a full tank. Also, make sure you know how far off your odometer is. My tires are tall so mine reads low. I've never seen one be correct. Once I multiply my odometer reading by the calculated constant I'm much happier.
P.S. Get a vacuum gauge for additional instant analog information. I use my vacuum gauge more than I look at MPGuino.

[TooMuchGlass]

Huh, ok I'll do that. But how the heck do I go about finding my odometer's margin of error?

[doviatt]

On your trip....note the odometer reading coincidence with a mile marker. Then (the more miles the better) see what it reads after 10 miles or so.
Example: smaller tire or high odo reading.
Start: End:
ODO: 252.3 ODO:262.5 = 10.2 miles
Mile marker 10 Mile marker 20 = 10.0 miles

10.2 odo miles divided by 10 actual miles = 1.02 Take the inverse of this 1/your number 1.02 = Calibration number is .980
Every time you fill up multiply your odometer reading by .980 to get your actual miles. (example 157.8 miles X .980 calibration = 154.64 actual miles.)

Edit: oops you could have also divided the 10.0 by 10.2 for the same result. Sorry. Not thinking straight.

If your odometer is off the other way or your tire is larger your odo number will read lower numbers and the calibration number will need to be greater than 1.0. My calibration number ends up being 1.0595.

Also verify this with a GPS and or Google maps. Your route to work would be a good one to use as it is the same every day. The GPS, the google map route, the MPGuino, and the odometer with the calibration should all now agree.

[TooMuchGlass]

Filled her up yesterday.
297 miles, nearly allot which we're highway, used up 6.849 gallons, for an average of 43. I can certainly work with that! My SG was about 8% optimistic, but it knows better now.

[MetroMPG]

Originally Posted by MetroMPG

Mine reads about 7-8% optimistic on fuel use, if I recall.

Separated at birth!