That seems odd.....

[b00f12]

With the recent discussions regarding Fuel Consumption, I have started driving around with the "l/100kms" showing on the MFD.

Unfortunately, I get to sit in my car for quite some time every morning and afternoon in peak hour traffic.

This afternoon I saw the l/100kms start to tick over UPWARDS while I was stationary. At first I thought I was seeing things..... then I got film.

http://members.iinet.net.au/~jaskatjacemm//video/golf_fuel_usage.mov

I would have though an idling car would be using less fuel.

Is this normal? Does it happen to everyone? Am I missing something? Or is this a WTF for the service department?

Jason.

 

[ONGIE]

mmmm...haven't seen that b4....i will pay attention to it tomorrow.

 

[japtaxi]

lol that looked funny as.. I have not seen it in my car last week when I watch it in "l/100km" mode :iono:

if it happens all the time then best pay vw service a visit

 

[Patchy]

If i clutch in and coast, my L/100km (instantaneous not average) starts at 0 (cause accerelator is off) then rises much like that until i reach a dead halt then it will become L/hr, didnt think too much of it....

 

[richardnau]

I would have though an idling car would be using less fuel.

When you are stationary, you are using fuel but going nowhere.

Fuel consumption displayed is averaged over some period of time: fuel used divided by distance covered. If you are stationary, distance covered doesn't increase but fuel used does, so reported consumption will increase.

 

[vwgtimkv]

When you are stationary, you are using fuel but going nowhere.

Fuel consumption displayed is averaged over some period of time: fuel used divided by distance covered. If you are stationary, distance covered doesn't increase but fuel used does, so reported consumption will increase.

x2.

Can't believe nobody else thought of it this way. The rate of fuel consumption is an average ratio (consumption/distance). When you are stationary at the lights, the additional distance travelled is 0 (you are adding nothing to the denominator of the ratio), but when the engine idles you are still using a baseline quanitity of additonal fuel (adding something to the numerator of the ratio) - therefore the total number (ie. fuel consumption) becomes larger.

Something else interesting to note RE. fuel consumption is the following interesting scenario:

Which one do you think would use more fuel (no throttle application under both scenarios)?:

A. Coasting down a steep hill in Neutral with revs at 1000rpm.
B. Descending the same hill in 3rd gear with revs at 4000rpm.

Your brain thinks option B is the obvious choice - higher revs equates to a higher level of fuel consumption ordinarily. But when engine braking, with no throttle application, the natural mechanical linkage between the wheels and the pistons is such that no ignition is required to keep the engine reciprocating (gravity turns the wheels, which turns the driveshafts, which transmits to turn the crankshaft and hence the pistons). As a result, the engine cuts the fuel injectors when engine braking with no throttle. Under option A, there is no mechanical linkage between the wheels and the engine - therefore there is nothing to keep the engine from stalling, therefore a certain level of combustion must take place. So next time you think you're saving fuel by coasting down a steep descent in neutral - pop the car back into gear, because you'll use less fuel. :thumbsup:

Cheers

 

[Lima]

Normal.

If you're stationary for long enough the readout should change to litres/hour as well.

On the MINI's instantaneous readout if you reset immediately after starting up you can sometimes get it to max out it's reading, which on the MINI, for some reason is 39.9l/100km.

 

[-mission-]

With the recent discussions regarding Fuel Consumption, I have started driving around with the "l/100kms" showing on the MFD.

You guys and your fancy highlines

 

[Sammy-Blue]

Normal.

If you're stationary for long enough the readout should change to litres/hour as well.

On the MINI's instantaneous readout if you reset immediately after starting up you can sometimes get it to max out it's reading, which on the MINI, for some reason is 39.9l/100km.

39.9???? That's not much.

 

[DRMAT]

You guys and your fancy highlines

Errr... you don't need the highline to see this.

 

[Yandi]

Don't be embarrassed BOOF................. naaah, be embarrassed. That was the most Irish entry for quite a while. Think of another...I bet you can!

 

[b00f12]

You guys and your maths.....

It makes a world of sense once you stop looking at it as the consumption of fuel and think of it as an equation.

Jason.

 

[Lima]

39.9???? That's not much.

Agreed. I'd suggest it's more of a fake limit so people don't think their little MINI is chewing the juice. :laugh:

Mind, the whole fuel consumption readouts on the MINI are that inaccurate it probably doesn't matter anyway.

 

[vwgtimkv]

Yet again, maths saves the day!

Cheers

 

[Sammy-Blue]

Yet again, maths saves the day!

Cheers

Hooray!