Slightly optimistic MPG computer

[Arik07]

Second week of owning my 07 4R and I realized I had an on board MPG computer. Filled up yesterday and reset the thing. On my way to work it was showing me an avg 26 and change MPG with occasional 28. Overall the ride to work was 33 MPG. Going home it had dropped down to 23 - 24 and this morning on the way to work it was at 22 and change. We'll see what the avg says when I get home.

The first week I had it I filled up and zeroed out the tech. On Monday I had a 1/4 left. Filled up again and divided the mileage driven by the gallons filled and got a little over 19 MPG

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[nevada]

I haven't reset mine in several years. it shows 18.3. my last few tanks averaged 19+ hand calculated. a few tanks prior to that, I was seeing around 17. at that time the dash was showing 18.2.
at best its a loose guideline lol.

 

[Arik07]

at best its a loose guideline lol.

"Loose" is a loose term in this case lol. I always treated them as a guestimate but dang.... almost 10mpg difference at one point!!

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[AuSeeker]

When you reset the MPGs readout it's somewhat close to what you're getting at the outset,...BUT everytime you stop, step a bit too hard on the gas you lose MPGs, as long as you are driving with no stops, no slowing down, easy on the gas the readout will look great and is generally a bit more than your actual MPGs at that moment, but that's not the real world, there are traffic lights, stop signs, and the ever constant desire to give it a bit more gas to get around that very slow driving person in front of you and no way it seem to get by them without stomping the gas to the floor and GOING!!

If you don't reset the MPG readout it will reach a constant and pretty much stay there, abeit it still will be very optimistic from what you're actually getting in the real world, the only thing I reset when I fill up and pay attention too is my average speed readout, the higher it is towards the end of the tank full the better your actual MPGs, that of course is to a certain point, if that average speed readout at the end of the tankful says 85 MPH to 100 MPH you will of course not be geting very good gas mileage!!

 

[tom4416]

I've owned my 03 since new and it has always been widely optimistic by the time it gets to the third or fourth tank of gas without a reset - often 3mpg over actual. I bought a Scangauge for a number of reasons, one of which was the ability to offset the mpg reading to get it spot on. The only time the factory setup is accurate is when I fill up at the beginning of a road trip, reset it and then do a consistent 60mph on the freeway. It will get 23mpg every single time assuming it's an extended trip on said freeway and that always agrees with both the Scangauge and the manual calculation.

 

[Berty_K]

Mine has always been on the optimistic side as well, by 2-3 mpg. I do a ton of city driving, so I see a lot of stop and go traffic. I average 14 mpg but the screen reads between 16 and 17.

 

[Arik07]

If you don't reset the MPG readout it will reach a constant and pretty much stay there!!

Exactly what I've noticed. My first week on a full tank I didn't reset anything because I thought it acted like newer cars where the MPG moves real time up or down depending on how you're driving at that moment. In the spring my Corolla was in for 5 recalls and the dealer have me a brand new Tacoma 4x4 TRD sport PRO... or something. That truck would show like 11mpg as I started from a red light and eventually get to about 17. My Corolla is like this too.

So I figured this would be the same idea. So my first tank the mog read between 19 and 19.5 which is about what I got overall. On the second tank I did a reset and thats when it jumped up to like 27. My driving habits in this truck don't change. Pretty much do speed limit and slow to accelerate. I stay with traffic but don't try to catch up with anyone Now, on the 3rd day it's down to 21mpg and I'm almost through the first quarter tank. Not that I really care. I knew what I was buying and this isn't going to be my daily ride. I'm just driving it now while it's still has that ....new to me...feel, as well as to get to know the car and it's noises. That way I'm not worried later if I hear or feel something. My daily is a 2010 Corolla. I just thought it was kinda funny.

After this week ill probably start to do some minor work to it

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