DIM average mpg goes down while at stop light

[oragex]

Is that normal? Sometimes the mpg really decreases, say from 25 would go down to 20 while waiting at a stop light for a minute. Other times it doesn't change.

[Orca2]

I read somewhere that mpg figure goes down even when stopped because you are still consuming fuel but not covering miles, it skews the average quite badly.

[TXC]

At 0mph will cover 0 miles per gallon of fuel, therefore it is the least efficient state for the car to be in ever.

Even if you are giving it good spanking playing racing cars and the like, you are getting more work done for your fuel than idling, idling =100% waste (in terms of getting somewhere).

Hence the introduction of stop-start strategy in many cars built over the last 3-4 years.

[Brendan W]

Of all the features in the modern car this one is high on my list of disable - way ahead of drls. It seems to distract more than its worth, gets attention way ahead of it's importance - wasted eyes down time imho. The fuel guage and trip as a back up should be more than adequate. Have hard lines on when to fill and don't let a silly algorithm tempt you to run low.

[100K+]

Originally Posted by Brendan W

don't let a silly algorithm tempt you to run low.

shucks ....this is one of my favourite toys ....lol

Cheers

Bob

[Orca2]

Would have to agree,forget about mpg if it bothers you buy a Micra,lol.

[Brendan W]

Originally Posted by 100K+

shucks ....this is one of my favourite toys ....lol

Cheers

Bob

Keep in in the box with Buzz and the Lego

[oragex]

Originally Posted by Orca2

I read somewhere that mpg figure goes down even when stopped because you are still consuming fuel but not covering miles, it skews the average quite badly.

Indeed, at times it goes down at a slow rate, which seems normal.

But sometimes it drops so fast, just like I was racing the engine. Or the engine is at idle at that moment.

[Simon Jones]

When was the last time you reset the average MPG? If you've just reset it, then the reading will fluctuate, but if it was done several tanks ago, then the reading should be pretty stable.

[Bill_56]

Originally Posted by Simon Jones

When was the last time you reset the average MPG? If you've just reset it, then the reading will fluctuate, but if it was done several tanks ago, then the reading should be pretty stable.

Correct answer, 100% agree.

I personally never, not ever, reset mine. It does seem to get reset during serices, after which, by the end of 500-1000 miles it is not unduly influenced by short term variables, like driving uphill, coasting downhill, or red traffic lights.

Moreover, by the end of 500-1000 miles it will be displaying a figure that is within 5% or 10% of the 'true' mpg, measured at my wallet!