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Discussion Starter · #1 ·
When I have my Trip computer set to show me my current gas mileage it will jump from 13 to 26 to 112 to 34 etc.. Is this correct? According to the VW salesmen and mechanic it is a crappy feature that VW should never of installed. Somehow I do not believe them.
2001.5 variant 4motion
 

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Thats correct...figure if you are pressing the gas it will increase its gas consumption. If you are coasting the car is basically idling and not using any power since there is no load thus high mpg. The best thing to do is drive it on the average that way you get an idea of how you are doing on a trip. It is a sorta useless feature but you can watch it when you floor the car and see how few mpg you can get out of the car.
 

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kaufmh said:
According to the VW salesmen and mechanic it is a crappy feature that VW should never of installed.
I think it's a valuable feature -- and reasonably accurate. I get instant feedback on how my driving habits affect my gas mileage.

Somehow I do not believe them.
You learn quickly, young padewan! :lol: :thumbup:
 

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Discussion Starter · #6 ·
I would agree with you if the changes weren't so dramatic, when your
on a flat road with constant pressure on the pedal and the computer is jumping from 20 to 50 it seems a bit useless.
 

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kaufmh said:
I would agree with you if the changes weren't so dramatic, when your
on a flat road with constant pressure on the pedal and the computer is jumping from 20 to 50 it seems a bit useless.
Your foot is not as constant on the pedal as you would think. If you re-drive the same strech of road with the cruise control on, instant MPG will fluctuate significantly less.

In addition, the road levelness, road surface, and wind speed are not constant. A 1% hill vs. a 1% slope makes a difference of 5 MPG or more. Rough pavement can use up another 2-5 MPG. I'd bet most of the guys who post 30+ MPG for their commute are on smooth blacktop most of the way.

Our engines monitor fuel delivery very closely -- it is a simple matter for the ECU to calculate fuel flowrate based on injector timing and fuel rail pressure.
 

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Discussion Starter · #8 ·
With all of these outside variables and the wild fluctuations why or how is this feature usefull? I don't mean to be argumentative but when your readings go from 20-30-60 in the space of 10 sec how can anyone pull some usefull data from that? Just curious
 

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It's just one more piece of data for the big picture... If I'm averaging 22mpg at each fill-up, but my instantaneous mpg shows 28-32 while i'm cruising on the highway, I know that I must really be stepping on the gas at traffic lights and such.

Another way to look at it... minor acceleration/deceleration causes wild fluctuation in gas consumption -- further reinforcement of why cruise control tends to give better gas mileage than foot-on-the-pedal, especially on long trips.

You also can see how cruising at 80mph uses much more gas than cruising at 60mph.

It's just data. You don't *have* to use it. Personally, I feel "out of touch" when I drive my wife's honda and don't have all the fuel data at my fingertips.

EDIT: If you're seeing 20-30-60 in the space of 10 seconds, that usually coincides with lifting your foot off the throttle... think of the data as "feedback" for your pedal inputs.
 

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its an okay feature imho

it give you pretty good feedback but it doesnt let you get a look at the big picture

just put it on avg and read that

you should be fine.
 
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