MPG What the hell???

[ArtemLepilov]

Today i was driving in worcester, MA and my AVG MPG was about 12!!! Note that i got new filters, oil, etc... Im driving on the highway... and as i pass trafiic i reset the computer and it stays at about 11-12 for a while and then it shoots up like crazy - get to 50 and beyond. Stays at 37 for a long while after sloowly going down from 50 and then levels off in the very end at 26.7

Now before it happened i was getting a normal MPG of about 24-27 on a regular freeway at 80-85MPH (Car feels awesome after an alignment...) But still pulls to the left a little (my rear toe is off a little..)

Now does someone have an explanation for that? can I trust my computer that tells me that either im driving a Boeing 747 or a Mini Cooper. Is there anything that could be causing the computer to tell me that?


-Artem

[uscharalph]

Today i was driving in worcester, MA and my AVG MPG was about 12!!! Note that i got new filters, oil, etc... Im driving on the highway... and as i pass trafiic i reset the computer and it stays at about 11-12 for a while and then it shoots up like crazy - get to 50 and beyond. Stays at 37 for a long while after sloowly going down from 50 and then levels off in the very end at 26.7

Now before it happened i was getting a normal MPG of about 24-27 on a regular freeway at 80-85MPH (Car feels awesome after an alignment...) But still pulls to the left a little (my rear toe is off a little..)

Now does someone have an explanation for that? can I trust my computer that tells me that either im driving a Boeing 747 or a Mini Cooper. Is there anything that could be causing the computer to tell me that?


-Artem
Were you any traffic? Uphill / downhill?

[ArtemLepilov]

Were you any traffic? Uphill / downhill?

During the low MPG i was in traffic and uphill downhill continuously, but i still tried to drive like a grandma. I also had the gas tank almost completely emptied last time, do you think that could influence the car somehow? I dont even know the capacity of it... And I put in about 19 gallons in just before leaving for worcester... (A 40 minute drive from Boston)

Also - how about the 50MPG spike... it wasnt like it just showed it and then it was gone, it was showing me 50 to 40 for a few minutes averaging ~39 in the end.

-Artem

[Qsilver7]

An average is taken from a set point in time to another set point in time. When you hit the reset button...you began a "new" average starting at that point (0 miles). Depending on the engine's load, the type of traffic you were driving in and the terrain...all of these things affected your avg mph. The more you drove...the more input and variables were enterered which again affected the AVG MPH that the OBC was showing. You can also look at the instant gas meter (in the tachometer gauge) and see what your gas usage is at that moment.

If you have very little load on the engine traveling on the highway drifting in a nice long slip stream ... down hill to boot...you can easily register 30, 40, 50 mph...especially if you just reset the AVG MPH (which is beginning a new average).

What does it show if you hit AVG MPH 2 (if it hasn't been reset)? If it hasn't been reset...I bet it will give you an average that you'd be more comfortable with.

I hope this makes sense. :D

[ArtemLepilov]

Yea, makes perfect sense... It just seemed to be going at a high MPG for a little too long, and the low MPG seemed pretty damn low. The long term average seems to be about 18MPG... which isnt that great and it seems to be a little worse than what I want to expect from the car.. but i suppose the weare and etc.. on the car does that to it. That injection cleaner thing I was looking into however I am really uncertain if it actually works or not... Has there been any proof that it works? Anyone tried it?

-Artem

[SRR2]

The only mileage calculation I'd worry about is the one derived from elapsed miles and fuel into the tank. The OBC is only an approximation, based on quite a few assumptions.

[Kalevera]

Exactly!

[liquidtiger720]

I find my obc to be fairly accurate. within 1-2 mpg compared to the
(overall milage/gallons)

[E34-520iSE]

The "Swingometer" on my dash cluster used to be frighteningly accurate. It would show anything from 0 MPG (on VERY steep hills it should show Gallons Per Mile) to 40-50 MPG on long fast downhill gradients. You may notice large needle deflections for small throttle movements, which seems odd but it is correct. I've disabled my guage now, I got sick of looking at it!

Cheers,

Shaun