Lexicon1

I just started driving my wife's SC 97 400.
On a fairly flat road, the mpg readings fluctuated from 27 mpg to 36 mpg.
There was only the slightest increase in slope.
Are these gauges as accurate as scangauge or is our computer readout bogus ?

O. L. T.

iTrader: (17)

That's not average MPG, that's real time MPG and it is accurate as it works off the throttle consumption. Any other gauge will simply read from the same sensor.

Lexicon1

ON a freeway, I am seeing a readout of typically 25-35 mpg and in real life I am lucky to get 20mpg

O. L. T.

iTrader: (17)

change your wheels or tires from stock size?

Lexicon1

OLT,
The issue is not that the mpg may be off a small percentage due to the non-stock tire.
What I am asking is,
Is the real time digital readout supposed to fluctuate that much on a "fairly level" surface. As the level goes uphill, the mpg goes down, this does make sense, but
at going 65 mpg, my readout claims I should be getting closer to 30 mpg which is no where near what is accurate in "real life".
So, is the Scangauge a better tool or computer than our stock system?

kyoso23

Click your mode button a few times to see your average. The real time one is only giving you a reading for that very second not an average. I reset my average mpg clock on every tank, it's usually between 23-25 mpg for the whole tank on my SC400 (with the AC on). The gauge on the car will be every bit as accurate as any of the aftermarket gauges assuming your overall tire diameter hasn't really changed.

Lexicon1

Kyoso, are you actually getting 23-25 mpg from every tank?
And, if you calculate manually, eg: total miles divided by total gallons of tank , do they match ? That is pretty good for a V8.

So, for each tank, I need to "hold in" the button for average mph, mpg , trip etc?
Sorry for asking this neophyte question.

Thanks

kyoso23

I think the V8 may be more efficient in that you don't have to give it as much juice to get going. That and the 1uZ was designed for efficiency and longevity moreso than power. I do probably do more highway driving than city, but they're always mixed tanks nonetheless. I can get upwards of 30 on the highway if I'm careful. I have calculated it manually in the past, but that's not ever perfect either as the pump shuts off at different times etc... It comes out really close though. I usually get ~340-360 miles per tank before I fill up. I always reset all that info for every tank, as you can see all the stats for that tank alone. The longer you let it run, the more of an overall average you're computing though. I reset the timer, AV mph, and AV mpg every time (by holding the button down on that screen).

atx

iTrader: (1)

I have been monitoring MPG closely over the past few months... Every time I run a comparison between a manual calc of miles/gallons with which I fill up and the computer, the average is at most .3 MPG different than the built-in computer average. That being said, I would say it is fairly accurate...

City driving yields terrible MPG on these things... revving over 3k often can put you at 15MPG, easy. I have been taking it easy the past few weeks and can now average ~18mpg with mixed city/hwy driving (usually get 24MPG on the highway).

O. L. T.

iTrader: (17)

If your gear ratio has changed form say... a TIRE CHANGE and it is running faster than it should any change is multiplied when the load is changed, but since you'd rather answer your own questions rather than mine,............. be my guest.

Lexicon1

OLT.
I answered your question.Potenza 225/50/16 is the tire size.
Yes, There was a tire change, there is a 3.46 % difference in speed.
There are 808 revolutions per mile on the stock tires , and 837 revolutions per mile on my tires.
It would appear that , if what you say is true , is true,
And if you said its true, therefore you must be correct, there is a fairly large fluctuation in mpg in real time mode even on fairly small height changes in road surface.
No one is doubting your knowledge. You are still the king here.
It was just a question.
....and have a great day.

TecnoSmurf

iTrader: (2)

Does the sc400 have a bigger tank?