I noticed something with the Average Fuel Consumption (AFC) on my vRS today.

When standing still in a "traffic jam" (with the engine on ofcourse), the AFC increases by a factor of 0.1 in a very short amount of time (i.e. 10,1 l/100km 3 sec later 10,2 etc).

Now if you ask me, i can't put the mathematics for this AFC figure. Why would it increase just by standing still, when the fuel consomption is around 1,0 l/h??

Anyone with an answer to this?

Cheers,

FD

not sure exactly but doesnt an increase in litres per hour equate to poorer economy... which would be correct if you are stationary with the engine running..

I've noticed this on my 1.6 also. But I've noticed something else as well so here are a couple of further observations.

I notice this most when viewing the AFC 1, the one that resets itself if you leave the car more than about 90 minutes. Also the effect is more noticable in the early parts of a journey, when consumption is naturally higher (cool engine) but even beyond then in the early part of a journey idling still has a proportionately greater effect on the consumption. Equally as soon as you get to steady speed driving the figures improve quite quickly.

Currently my AFC 2 is up around 3000 miles; 85+hours; and 34.7 mpg; if I leave the display set to AFC 2 then I don't see these variations, since they have proportionately less effect on these larger totals.

But watching AFC 1 does focus the mind on the more inefficient parts of your journey. If you are inclined to want to run economically the AFC (MFA) gives you plenty of information to use in developing an economical style.

I'm sure these finer points of economy are not an issue for most vRS divers, that's not why you buy the car, however in a modest 1.6 there's not quite so much excitement, so playing with the AFC helps pass the time :D:D

Paul

Litres per distance will increase when stationary, as petrol is being used idling and at no increase

in distance.

This accounts for the rapid increase in the figure when stationary - it's a division by zero.

Rob.

if you divide by zero don't you get infinity???

Paul

Indeed...which is a hell of a steep increase!

Rob.

A glitch in the AFC calculator?

/FD

im sure the computer is not quite that stupid....

Wouldn't say it was a glitch, it's the way the maths works!

Rob.

No - it's working out the average over the journey. You are not adding any extra distance but the distance you have travelled so far is still in the divisor.

Originally posted by ffelan in this post

im sure the computer is not quite that stupid....

No the computer isn't, it's those of us who sit and watch the computer that are stupid, sad, missing something......I should know I am that sado:D

Like I said not much else to do in a 1.6...

Paul

Originally posted by ncarring in this post

No - it's working out the average over the journey. You are not adding any extra distance but the distance you have travelled so far is still in the divisor.

Hmm...OK, so I seem to be talking about the wrong thing...

Rob.

I'll never watch the AFC numbers anymore, it's only a sad figure saying "slurp slurp i like gasoline".

No, I'll just sit in my vRS, with the carstereo loud, a huge grin on my face and enjoy the ride

/FD

Originally posted by FightingDiva in this post

I'll never watch the AFC numbers anymore, it's only a sad figure saying "slurp slurp i like gasoline".

No, I'll just sit in my vRS, with the carstereo loud, a huge grin on my face and enjoy the ride

/FD

well said

I too have noticed the MPG fall quite sharply especially at about 160mph.

I don't even know how many mpg's mine does (or I do)... Am I missing out on something?

Motto for today: If you have to ask how much, you can't afford it

It's a function in the car nothing more nothing less. If you don't bother about fuel economy you probably never look at it.

/FD

Single trip memory 1 erases automatically if the trip (journey) is interrupted for more than 2 hours. Total trip memory 2 erases after 100 hours travelling time, 10,000km distance and 1000 litres of fuel. My trip 2 reset after circa 4000 miles and 590 litres of fuel while SWMBO was away on holiday with the car. She returned with trip 2 fuel consumption showing 39 mpg - which had me really intrigued since up to that point it had been reading 32.7 mpg. Guess she freewheeled for the final part of the journey after it had reset at 100 hours travelling time.